GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-23472 (GCVE-0-2026-23472)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-05-11 22:07
VLAI
Title
serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN
Summary
In the Linux kernel, the following vulnerability has been resolved: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < efe85a557186b7fe915572ae93a8f3f78bfd9a22 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 455ce986fa356ff43a43c0d363ba95fa152f21d5 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/serial/serial_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "efe85a557186b7fe915572ae93a8f3f78bfd9a22",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "455ce986fa356ff43a43c0d363ba95fa152f21d5",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/serial/serial_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
              "lessThan": "2.6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "2.6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.10",
                  "versionStartIncluding": "2.6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "2.6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN\n\nuart_write_room() and uart_write() behave inconsistently when\nxmit_buf is NULL (which happens for PORT_UNKNOWN ports that were\nnever properly initialized):\n\n- uart_write_room() returns kfifo_avail() which can be \u003e 0\n- uart_write() checks xmit_buf and returns 0 if NULL\n\nThis inconsistency causes an infinite loop in drivers that rely on\ntty_write_room() to determine if they can write:\n\n  while (tty_write_room(tty) \u003e 0) {\n      written = tty-\u003eops-\u003ewrite(...);\n      // written is always 0, loop never exits\n  }\n\nFor example, caif_serial\u0027s handle_tx() enters an infinite loop when\nused with PORT_UNKNOWN serial ports, causing system hangs.\n\nFix by making uart_write_room() also check xmit_buf and return 0 if\nit\u0027s NULL, consistent with uart_write().\n\nReproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:07:41.736Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22"
        },
        {
          "url": "https://git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c"
        },
        {
          "url": "https://git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5"
        }
      ],
      "title": "serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23472",
    "datePublished": "2026-04-03T15:15:51.209Z",
    "dateReserved": "2026-01-13T15:37:46.022Z",
    "dateUpdated": "2026-05-11T22:07:41.736Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-23472",
      "date": "2026-09-15",
      "epss": "0.00121",
      "percentile": "0.0219"
    },
    "microsoft_vex": {
      "current_release_date": "2026-06-28T02:05:08.000Z",
      "cve": "CVE-2026-23472",
      "id": "msrc_CVE-2026-23472",
      "initial_release_date": "2026-04-02T00:00:00.000Z",
      "product_status:known_affected": "7",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-23472.json",
      "version": "8"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23472\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-03T16:16:34.977\",\"lastModified\":\"2026-07-20T20:10:00.110\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nserial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN\\n\\nuart_write_room() and uart_write() behave inconsistently when\\nxmit_buf is NULL (which happens for PORT_UNKNOWN ports that were\\nnever properly initialized):\\n\\n- uart_write_room() returns kfifo_avail() which can be \u003e 0\\n- uart_write() checks xmit_buf and returns 0 if NULL\\n\\nThis inconsistency causes an infinite loop in drivers that rely on\\ntty_write_room() to determine if they can write:\\n\\n  while (tty_write_room(tty) \u003e 0) {\\n      written = tty-\u003eops-\u003ewrite(...);\\n      // written is always 0, loop never exits\\n  }\\n\\nFor example, caif_serial\u0027s handle_tx() enters an infinite loop when\\nused with PORT_UNKNOWN serial ports, causing system hangs.\\n\\nFix by making uart_write_room() also check xmit_buf and return 0 if\\nit\u0027s NULL, consistent with uart_write().\\n\\nReproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nserial: core: correcci\u00f3n de bucle infinito en handle_tx() para PORT_UNKNOWN\\n\\nuart_write_room() y uart_write() se comportan de forma inconsistente cuando xmit_buf es NULL (lo cual ocurre para puertos PORT_UNKNOWN que nunca fueron inicializados correctamente):\\n\\n- uart_write_room() devuelve kfifo_avail() que puede ser \u003e 0\\n- uart_write() comprueba xmit_buf y devuelve 0 si es NULL\\n\\nEsta inconsistencia causa un bucle infinito en controladores que dependen de tty_write_room() para determinar si pueden escribir:\\n\\n  while (tty_write_room(tty) \u003e 0) {\\n      written = tty-\u003eops-\u003ewrite(...);\\n      // written es siempre 0, el bucle nunca sale\\n  }\\n\\nPor ejemplo, el handle_tx() de caif_serial entra en un bucle infinito cuando se usa con puertos serie PORT_UNKNOWN, causando cuelgues del sistema.\\n\\nSoluci\u00f3n al hacer que uart_write_room() tambi\u00e9n compruebe xmit_buf y devuelva 0 si es NULL, consistente con uart_write().\\n\\nReproductor: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/tty/serial/serial_core.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"efe85a557186b7fe915572ae93a8f3f78bfd9a22\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2\",\"lessThan\":\"455ce986fa356ff43a43c0d363ba95fa152f21d5\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/tty/serial/serial_core.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.20\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19.10\",\"lessThanOrEqual\":\"6.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-835\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.6.12.1\",\"versionEndExcluding\":\"6.18.20\",\"matchCriteriaId\":\"C04EFB79-759E-465D-B79E-F062CD8CBD1B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.10\",\"matchCriteriaId\":\"96D34333-38BE-4414-9E79-6EB764329581\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*\",\"matchCriteriaId\":\"6F62EECE-8FB1-4D57-85D8-CB9E23CF313C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4F76C298-81DC-43E4-8FC9-DC005A2116EF\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"0AB349B2-3F78-4197-882B-90ADB3BF645A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"6AC88830-A9BC-4607-B572-A4B502FC9FD0\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"476CB3A5-D022-4F13-AAEF-CB6A5785516A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T07:21:10+00:00",
      "cve": "CVE-2026-23472",
      "id": "CVE-2026-23472",
      "initial_release_date": "2026-04-03T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23472.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T01:35:44Z",
      "cve": "CVE-2026-23472",
      "id": "CVE-2026-23472",
      "initial_release_date": "2026-04-03T23:27:01Z",
      "product_status:first_fixed": "2",
      "product_status:known_not_affected": "274",
      "product_status:recommended": "317",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-23472",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-23472.json",
      "version": "15"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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

Author Source Type Date Other

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.