CVE-2026-45842 (GCVE-0-2026-45842)
Vulnerability from cvelistv5 – Published: 2026-05-27 09:24 – Updated: 2026-05-27 09:24
VLAI
Title
slip: reject VJ receive packets on instances with no rstate array
Summary
In the Linux kernel, the following vulnerability has been resolved:
slip: reject VJ receive packets on instances with no rstate array
slhc_init() accepts rslots == 0 as a valid configuration, with the
documented meaning of 'no receive compression'. In that case the
allocation loop in slhc_init() is skipped, so comp->rstate stays
NULL and comp->rslot_limit stays 0 (from the kzalloc of struct
slcompress).
The receive helpers do not defend against that configuration.
slhc_uncompress() dereferences comp->rstate[x] when the VJ header
carries an explicit connection ID, and slhc_remember() later assigns
cs = &comp->rstate[...] after only comparing the packet's slot number
to comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the
range check, and the code dereferences a NULL rstate.
The configuration is reachable in-tree through PPP. PPPIOCSMAXCID
stores its argument in a signed int, and (val >> 16) uses arithmetic
shift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1
is 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because
/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path
is reachable from an unprivileged user namespace. Once the malformed
VJ state is installed, any inbound VJ-compressed or VJ-uncompressed
frame that selects slot 0 crashes the kernel in softirq context:
Oops: general protection fault, probably for non-canonical
address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)
Call Trace:
<TASK>
ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)
ppp_input (drivers/net/ppp/ppp_generic.c:2359)
ppp_async_process (drivers/net/ppp/ppp_async.c:492)
tasklet_action_common (kernel/softirq.c:926)
handle_softirqs (kernel/softirq.c:623)
run_ksoftirqd (kernel/softirq.c:1055)
smpboot_thread_fn (kernel/smpboot.c:160)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:164)
</TASK>
Reject the receive side on such instances instead of touching rstate.
slhc_uncompress() falls through to its existing 'bad' label, which
bumps sls_i_error and enters the toss state. slhc_remember() mirrors
that with an explicit sls_i_error increment followed by slhc_toss();
the sls_i_runt counter is not used here because a missing rstate is
an internal configuration state, not a runt packet.
The transmit path is unaffected: the only in-tree caller that picks
rslots from userspace (ppp_generic.c) still supplies tslots >= 1, and
slip.c always calls slhc_init(16, 16), so comp->tstate remains valid
and slhc_compress() continues to work.
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| Linux | Linux |
Affected:
4ab42d78e37a294ac7bc56901d563c642e03c4ae , < c6980e8b1a86288167f34966fa5219031999b6f1
(git)
Affected: 4ab42d78e37a294ac7bc56901d563c642e03c4ae , < de42f86e2cf5028a97e74c25869d1a962b13c301 (git) Affected: 4ab42d78e37a294ac7bc56901d563c642e03c4ae , < 9e1ff0eead073c4f46d874ad2526b7dda5465faf (git) Affected: 4ab42d78e37a294ac7bc56901d563c642e03c4ae , < 7b0d9e878ec2b21d99ae8051b3dda59cdb66c152 (git) Affected: 4ab42d78e37a294ac7bc56901d563c642e03c4ae , < e76607442d5b73e1ba6768f501ef815bb58c2c0e (git) Affected: 42fc512469e78939c1e419d3310c47de55bdcbb8 (git) Affected: df085f1cb3acd3d75408ff94f366983873bce7d2 (git) Affected: a1c3860d3c5fc62bd35f089bcb03f18a37242de9 (git) Affected: f82699de104eaf8a7ffc2849a566a94818dd8a3c (git) Affected: 354b254af5c1350de9586af75fe5a821b35bfb33 (git) Affected: 5148857f5d4c812cc918cf4627f7880521e987eb (git) Affected: 82185755d90c8047c6f4b589c39998ff3d4ca3ad (git) Affected: a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d (git) Affected: 6b4fa561e26526c62636414d267342c945084f44 (git) Affected: 2.6.32.70 , < 2.6.33 (semver) Affected: 3.2.75 , < 3.3 (semver) Affected: 3.4.111 , < 3.5 (semver) Affected: 3.10.96 , < 3.11 (semver) Affected: 3.12.53 , < 3.13 (semver) Affected: 3.14.60 , < 3.15 (semver) Affected: 3.18.27 , < 3.19 (semver) Affected: 4.1.17 , < 4.2 (semver) Affected: 4.3.5 , < 4.4 (semver) |
|
| Linux | Linux |
Affected:
4.4
Unaffected: 0 , < 4.4 (semver) Unaffected: 6.6.141 , ≤ 6.6.* (semver) Unaffected: 6.12.91 , ≤ 6.12.* (semver) Unaffected: 6.18.33 , ≤ 6.18.* (semver) Unaffected: 7.0.10 , ≤ 7.0.* (semver) Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix) |
{
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"versionType": "git"
},
{
"status": "affected",
"version": "a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d",
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{
"status": "affected",
"version": "6b4fa561e26526c62636414d267342c945084f44",
"versionType": "git"
},
{
"lessThan": "2.6.33",
"status": "affected",
"version": "2.6.32.70",
"versionType": "semver"
},
{
"lessThan": "3.3",
"status": "affected",
"version": "3.2.75",
"versionType": "semver"
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{
"lessThan": "3.5",
"status": "affected",
"version": "3.4.111",
"versionType": "semver"
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{
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"status": "affected",
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{
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{
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"versionType": "semver"
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"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/slip/slhc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.4"
},
{
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"versionType": "semver"
},
{
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"status": "unaffected",
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"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.91",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.33",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
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},
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nslip: reject VJ receive packets on instances with no rstate array\n\nslhc_init() accepts rslots == 0 as a valid configuration, with the\ndocumented meaning of \u0027no receive compression\u0027. In that case the\nallocation loop in slhc_init() is skipped, so comp-\u003erstate stays\nNULL and comp-\u003erslot_limit stays 0 (from the kzalloc of struct\nslcompress).\n\nThe receive helpers do not defend against that configuration.\nslhc_uncompress() dereferences comp-\u003erstate[x] when the VJ header\ncarries an explicit connection ID, and slhc_remember() later assigns\ncs = \u0026comp-\u003erstate[...] after only comparing the packet\u0027s slot number\nto comp-\u003erslot_limit. Because rslot_limit is 0, slot 0 passes the\nrange check, and the code dereferences a NULL rstate.\n\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\nstores its argument in a signed int, and (val \u003e\u003e 16) uses arithmetic\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\nis reachable from an unprivileged user namespace. Once the malformed\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\nframe that selects slot 0 crashes the kernel in softirq context:\n\n Oops: general protection fault, probably for non-canonical\n address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\n Call Trace:\n \u003cTASK\u003e\n ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\n ppp_input (drivers/net/ppp/ppp_generic.c:2359)\n ppp_async_process (drivers/net/ppp/ppp_async.c:492)\n tasklet_action_common (kernel/softirq.c:926)\n handle_softirqs (kernel/softirq.c:623)\n run_ksoftirqd (kernel/softirq.c:1055)\n smpboot_thread_fn (kernel/smpboot.c:160)\n kthread (kernel/kthread.c:436)\n ret_from_fork (arch/x86/kernel/process.c:164)\n \u003c/TASK\u003e\n\nReject the receive side on such instances instead of touching rstate.\nslhc_uncompress() falls through to its existing \u0027bad\u0027 label, which\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\nthat with an explicit sls_i_error increment followed by slhc_toss();\nthe sls_i_runt counter is not used here because a missing rstate is\nan internal configuration state, not a runt packet.\n\nThe transmit path is unaffected: the only in-tree caller that picks\nrslots from userspace (ppp_generic.c) still supplies tslots \u003e= 1, and\nslip.c always calls slhc_init(16, 16), so comp-\u003etstate remains valid\nand slhc_compress() continues to work."
}
],
"providerMetadata": {
"dateUpdated": "2026-05-27T09:24:42.637Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1"
},
{
"url": "https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301"
},
{
"url": "https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf"
},
{
"url": "https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152"
},
{
"url": "https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e"
}
],
"title": "slip: reject VJ receive packets on instances with no rstate array",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-45842",
"datePublished": "2026-05-27T09:24:42.637Z",
"dateReserved": "2026-05-13T15:03:33.078Z",
"dateUpdated": "2026-05-27T09:24:42.637Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-45842",
"date": "2026-05-28",
"epss": "0.00018",
"percentile": "0.05152"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-45842\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-27T11:16:23.600\",\"lastModified\":\"2026-05-27T14:48:03.013\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nslip: reject VJ receive packets on instances with no rstate array\\n\\nslhc_init() accepts rslots == 0 as a valid configuration, with the\\ndocumented meaning of \u0027no receive compression\u0027. In that case the\\nallocation loop in slhc_init() is skipped, so comp-\u003erstate stays\\nNULL and comp-\u003erslot_limit stays 0 (from the kzalloc of struct\\nslcompress).\\n\\nThe receive helpers do not defend against that configuration.\\nslhc_uncompress() dereferences comp-\u003erstate[x] when the VJ header\\ncarries an explicit connection ID, and slhc_remember() later assigns\\ncs = \u0026comp-\u003erstate[...] after only comparing the packet\u0027s slot number\\nto comp-\u003erslot_limit. Because rslot_limit is 0, slot 0 passes the\\nrange check, and the code dereferences a NULL rstate.\\n\\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\\nstores its argument in a signed int, and (val \u003e\u003e 16) uses arithmetic\\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\\nis reachable from an unprivileged user namespace. Once the malformed\\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\\nframe that selects slot 0 crashes the kernel in softirq context:\\n\\n Oops: general protection fault, probably for non-canonical\\n address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\\n Call Trace:\\n \u003cTASK\u003e\\n ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\\n ppp_input (drivers/net/ppp/ppp_generic.c:2359)\\n ppp_async_process (drivers/net/ppp/ppp_async.c:492)\\n tasklet_action_common (kernel/softirq.c:926)\\n handle_softirqs (kernel/softirq.c:623)\\n run_ksoftirqd (kernel/softirq.c:1055)\\n smpboot_thread_fn (kernel/smpboot.c:160)\\n kthread (kernel/kthread.c:436)\\n ret_from_fork (arch/x86/kernel/process.c:164)\\n \u003c/TASK\u003e\\n\\nReject the receive side on such instances instead of touching rstate.\\nslhc_uncompress() falls through to its existing \u0027bad\u0027 label, which\\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\\nthat with an explicit sls_i_error increment followed by slhc_toss();\\nthe sls_i_runt counter is not used here because a missing rstate is\\nan internal configuration state, not a runt packet.\\n\\nThe transmit path is unaffected: the only in-tree caller that picks\\nrslots from userspace (ppp_generic.c) still supplies tslots \u003e= 1, and\\nslip.c always calls slhc_init(16, 16), so comp-\u003etstate remains valid\\nand slhc_compress() continues to work.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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