netfilter: nf_conntrack_helper: pass helper to expect cleanup
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)
CVE-2026-43027
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-43027
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "5cf28d5c8dcbbe8af6d3b145babe491906d7bad1",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "504ba4168466c91210c45acdc332479cfd5f2da6",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "dc1739eff48e34cc71d4e2f03715493fbcebd8af",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "2cf2737c85a2ba2b52024dafe68ffad2676f97be",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "2c16e4d64dd91227742dfe196a3e7b0568bef65a",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "620f3d14c1ef51d425060a3056ad8dbae8f998a3",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "90bd7e8501349db3006d21fbc09df9ffcb172965",
"versionType": "git"
},
{
"status": "affected",
"version": "ac7b848390036dadd4351899d2a23748075916bd",
"lessThan": "a242a9ae58aa46ff7dae51ce64150a93957abe65",
"versionType": "git"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_helper.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.253",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.203",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.168",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.134",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.81",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.22",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "6.19.12",
"versionType": "semver",
"lessThanOrEqual": "6.19.*"
},
{
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_helper.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-43027
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #28339 · Revision 1
- Added to Heist Feed
- Publisher date