CVE-2026-43027 (GCVE-0-2026-43027)
Vulnerability from cvelistv5
Published
2026-05-01 14:15
Modified
2026-05-01 14:15
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_helper: pass helper to expect cleanup
nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()
to remove expectations belonging to the helper being unregistered.
However, it passes NULL instead of the helper pointer as the data
argument, so expect_iter_me() never matches any expectation and all
of them survive the cleanup.
After unregister returns, nfnl_cthelper_del() frees the helper
object immediately. Subsequent expectation dumps or packet-driven
init_conntrack() calls then dereference the freed exp->helper,
causing a use-after-free.
Pass the actual helper pointer so expectations referencing it are
properly destroyed before the helper object is freed.
BUG: KASAN: slab-use-after-free in string+0x38f/0x430
Read of size 1 at addr ffff888003b14d20 by task poc/103
Call Trace:
string+0x38f/0x430
vsnprintf+0x3cc/0x1170
seq_printf+0x17a/0x240
exp_seq_show+0x2e5/0x560
seq_read_iter+0x419/0x1280
proc_reg_read+0x1ac/0x270
vfs_read+0x179/0x930
ksys_read+0xef/0x1c0
Freed by task 103:
The buggy address is located 32 bytes inside of
freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd Version: ac7b848390036dadd4351899d2a23748075916bd |
||
{
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"version": "6.1.168",
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{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to the helper being unregistered.\nHowever, it passes NULL instead of the helper pointer as the data\nargument, so expect_iter_me() never matches any expectation and all\nof them survive the cleanup.\n\nAfter unregister returns, nfnl_cthelper_del() frees the helper\nobject immediately. Subsequent expectation dumps or packet-driven\ninit_conntrack() calls then dereference the freed exp-\u003ehelper,\ncausing a use-after-free.\n\nPass the actual helper pointer so expectations referencing it are\nproperly destroyed before the helper object is freed.\n\n BUG: KASAN: slab-use-after-free in string+0x38f/0x430\n Read of size 1 at addr ffff888003b14d20 by task poc/103\n Call Trace:\n string+0x38f/0x430\n vsnprintf+0x3cc/0x1170\n seq_printf+0x17a/0x240\n exp_seq_show+0x2e5/0x560\n seq_read_iter+0x419/0x1280\n proc_reg_read+0x1ac/0x270\n vfs_read+0x179/0x930\n ksys_read+0xef/0x1c0\n Freed by task 103:\n The buggy address is located 32 bytes inside of\n freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)"
}
],
"providerMetadata": {
"dateUpdated": "2026-05-01T14:15:28.521Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
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"url": "https://git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1"
},
{
"url": "https://git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6"
},
{
"url": "https://git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af"
},
{
"url": "https://git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be"
},
{
"url": "https://git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a"
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{
"url": "https://git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3"
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{
"url": "https://git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965"
},
{
"url": "https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65"
}
],
"title": "netfilter: nf_conntrack_helper: pass helper to expect cleanup",
"x_generator": {
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}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-43027",
"datePublished": "2026-05-01T14:15:28.521Z",
"dateReserved": "2026-05-01T14:12:55.976Z",
"dateUpdated": "2026-05-01T14:15:28.521Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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