CVE Intelligence
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CVE-2026-80843 — xfrm: fix xfrm_state_construct() auth-trunc leak

In the Linux kernel, the following vulnerability has been resolved: xfrm: fix xfrm_state_construct() auth-trunc leak attach_auth_trunc() can allocate x->aalg while leaving x->props.aalgo at zero when the selected auth algorithm has no sadb_alg_id. One real case is cmac(aes). xfrm_state_construct() then treats !x->props.aalgo as "no auth algorithm attached yet" and calls attach_auth(). That overwrites x->aalg and loses the first allocation. Any later failure or teardown only frees the replacement pointer. Check whether x->aalg is already attached instead of inferring that state from x->props.aalgo.

Published Sep 4, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

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 0.2% (30-day exploitation probability)+1

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
0.2%
ahead of 9% of scored CVEs · Oct 27, 2026
Affects
Linux
Linux
CVSS base
—
Score not published yet.

Remediation

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

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < 958ae9f261319e1cdc44879886bcda2263258cca≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < fb7f3e74789a3c89647f4eb768f6dfaf4a751e72≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < ba0c110c205855b3f1e3130d8c0fdb484d704c8c≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < c8837bbe792257af547fd1c0252553ce13148795≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < 71d42da01740ec6557837bebec0bc48cfc3b4c39≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < cf67361e78dca488d6e4df8396a53e6745a3a80e≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < 37426395cb90ef217beec8407a14bd82153793d3≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < be19d20e53a239572bb2a28efcc1cd2b069b1ef9
and 2 more ≥ 4447bb33f09444920a8f1d89e1540137429351b6 and < c12cbf56320fb633484ee0ca1fb7d68d6b64b213version 2.6.33
Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 27, 2026 · 12 reading(s) · max 0.20%

Detection

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

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Record published
    Oct 15, 2026
  • Affected products added · linux/linux
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 4, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 19, 2026 – Oct 19, 2026
  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

11 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-99215 power: supply: core: prevent unregistering a power supply while a callback runs 12h
  • CVE-2026-99216 Drivers: hv: Don't reset VMBus connection state on error/exit paths 12h
  • CVE-2026-99214 drm/vc4: hdmi: Move packet RAM enable to PM runtime 12h
  • CVE-2026-99207 scsi: target: Disable interrupts while holding delayed_cmd_lock 12h
  • CVE-2026-99208 drm/xe/oa: Zero OA buffer at allocation 12h
  • CVE-2026-99209 drm/xe: skip eviction of a BO with no resource 12h

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 CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • 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-2026-80843 is "xfrm: fix xfrm_state_construct() auth-trunc leak", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.20% 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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