High Memory corruption

CVE-2026-43027 — 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)

Published May 1, 2026 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.1% (30-day exploitation probability)+0
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.13%

ahead of 2% of scored CVEs · Oct 14, 2026

Affects

Linux

Linux and 1 more

CVSS base

7.8

High · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)
Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	version 4.14≥ ac7b848390036dadd4351899d2a23748075916bd and < a242a9ae58aa46ff7dae51ce64150a93957abe65≥ ac7b848390036dadd4351899d2a23748075916bd and < 90bd7e8501349db3006d21fbc09df9ffcb172965≥ ac7b848390036dadd4351899d2a23748075916bd and < 620f3d14c1ef51d425060a3056ad8dbae8f998a3≥ ac7b848390036dadd4351899d2a23748075916bd and < 2c16e4d64dd91227742dfe196a3e7b0568bef65a≥ ac7b848390036dadd4351899d2a23748075916bd and < 2cf2737c85a2ba2b52024dafe68ffad2676f97be≥ ac7b848390036dadd4351899d2a23748075916bd and < dc1739eff48e34cc71d4e2f03715493fbcebd8af≥ ac7b848390036dadd4351899d2a23748075916bd and < 504ba4168466c91210c45acdc332479cfd5f2da6 and 1 more ≥ ac7b848390036dadd4351899d2a23748075916bd and < 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1	Vulnerable	CVE Program (cve.org) e CISA ADP
Linux	Linux Kernel	version 7.0-rc5version 7.0-rc6≥ 4.14 and < 5.10.253version 7.0-rc4version 7.0-rc3version 7.0-rc2version 7.0-rc1≥ 6.19 and < 6.19.12 and 5 more ≥ 6.13 and < 6.18.22≥ 6.7 and < 6.12.81≥ 6.2 and < 6.6.134≥ 5.16 and < 6.1.168≥ 5.11 and < 5.15.203	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.8	CVSS 3.1	High	1.8	5.9	nvd@nist.gov via NIST National Vulnerability Database
7.8	CVSS 3.1	High	—	—	GitHub, Inc. via GitHub Security Advisories

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-416 · Use After Free

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.13%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 7.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 1, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 14, 2026 – Oct 14, 2026
1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

13 on the record

git.kernel.org/stable/c/90bd7e8501349db3006d21fbc09df9ffcb172965
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/5cf28d5c8dcbbe8af6d3b145babe491906d7bad1
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/620f3d14c1ef51d425060a3056ad8dbae8f998a3
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/2cf2737c85a2ba2b52024dafe68ffad2676f97be
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/dc1739eff48e34cc71d4e2f03715493fbcebd8af
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/2c16e4d64dd91227742dfe196a3e7b0568bef65a
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/504ba4168466c91210c45acdc332479cfd5f2da6
Patch, NIST National Vulnerability Database
github.com/advisories/GHSA-f42g-qv35-qm2v
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-43027
GitHub Security Advisories
cert-portal.siemens.com/productcert/html/ssa-082556.html
NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-457936.html
NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-019113.html
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Memory corruption
same class

CWE-416
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CISA SSVC assessment.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-43027 is "netfilter: nf_conntrack_helper: pass helper to expect cleanup", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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