CVE-2026-43027: netfilter: nf_conntrack_helper: pass helper to expect cleanup

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• linux linux kernel4.14 and later · before 5.10.253
• linux linux kernel5.11 and later · before 5.15.203
• linux linux kernel5.16 and later · before 6.1.168
• linux linux kernel6.2 and later · before 6.6.134
• linux linux kernel6.7 and later · before 6.12.81
• linux linux kernel6.13 and later · before 6.18.22
• linux linux kernel6.19 and later · before 6.19.12
• linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

• Linux Linux

  • 4.14affected
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1affected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 504ba4168466c91210c45acdc332479cfd5f2da6affected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before dc1739eff48e34cc71d4e2f03715493fbcebd8afaffected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 2cf2737c85a2ba2b52024dafe68ffad2676f97beaffected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 2c16e4d64dd91227742dfe196a3e7b0568bef65aaffected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 620f3d14c1ef51d425060a3056ad8dbae8f998a3affected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before 90bd7e8501349db3006d21fbc09df9ffcb172965affected · git
  • ac7b848390036dadd4351899d2a23748075916bd and later · before a242a9ae58aa46ff7dae51ce64150a93957abe65affected · git
  • before 4.14not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
  90Now
• CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
  89Now
• CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
  85Now

Published before and after this one in the same product

• ← EarlierCVE-2026-43025May 1, 2026 · netfilter: ctnetlink: ignore explicit helper on new expectations
  29Monitor
• ← EarlierCVE-2026-43026May 1, 2026 · netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent
  22Monitor
• Later →CVE-2026-43028May 1, 2026 · netfilter: x_tables: ensure names are nul-terminated
  28Monitor

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1free(dev->buf);2/* ... another thread is still running ... */3process(dev->buf);

1lock(&dev->lock);2free(dev->buf);3dev->buf = NULL;4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.