CVE Intelligence
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CVE-2026-80808 — ext4: stop retrying saturated xattr cache entries

In the Linux kernel, the following vulnerability has been resolved: ext4: stop retrying saturated xattr cache entries ext4_xattr_block_set() retries when a cache entry selected for reuse has a saturated reference count after taking the buffer lock. The retry returns to the mbcache lookup without making that entry ineligible, so it can select the same unusable entry indefinitely. A task spinning there can hold the parent directory's i_rwsem and leave concurrent rmdir callers blocked. Normally a reusable entry has a reference count below EXT4_XATTR_REFCOUNT_MAX because the count and MBE_REUSABLE_B are updated under the same buffer lock. A corrupted filesystem can violate that invariant. The syzbot reproducer reports allocator and xattr corruption before triggering this retry loop. Check the untrusted on-disk count before incrementing it, avoiding overflow, and clear MBE_REUSABLE_B when it is already saturated. The next lookup then skips the entry that was just proven unusable. This mirrors the normal transition at EXT4_XATTR_REFCOUNT_MAX; the release path marks the entry reusable again on the exact 1024-to-1023 transition. Using the same QEMU harness and guest parameters, current unpatched Linux hung in 6 of 8 420-second trials with the do_rmdir signature; representative NMI backtraces caught the owner spinning in ext4_xattr_block_set(). The patched kernel completed 28 of 28 trials without a hung-task report; the final twelve trials exercised the reviewed overflow-safe form of the change. syzbot's patch testing also completed without reproducing the hang.

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 25, 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 version af8ecc8d20e72130771cc076bce7fcf17ccda6c4version 6.0≥ 5.19.2 and < 5.20≥ 5.18.18 and < 5.19≥ 5.4.229 and < 5.5≥ 4.19.270 and < 4.20≥ 5.15.61 and < 5.15.218≥ 5.10.163 and < 5.10.267
and 12 more version 96fa141fa295ae9428da73c56c9852053b575c04version c6fac5cf5a5098732623bcd00a8a3eb9f5465144≥ 1a56cd972ce121b6cf2517a47a578782bbd2ec95 and < 119a2f053242ed75bdd2ebc95baf3ae7db6ccacfversion 98953044b3cdb2cb7d82e7365b659e2ed4f4ca4d≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < 54b6bd40898de7906acb2bccc9a96d1b8e6b4323≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < dbd4aea175ad3c46436acb251e817b4374628072≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < 55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < 4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < 889ec86464d261f026f6c334040cfc6c58c99d58≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < a40c45268f4358207aa9c53764fed2e05f62986a≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b and < 8865cd664484517703df5c18a965dc3227572b87≥ 1be97463696c7291a3e1547614e96432b0bd3add and < 61631352a5b405c89be579de00903b72e6888aa4
Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 25, 2026 · 10 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-2026-99092 riscv: patch: fix handling of bpf-jit execmem addresses 11h
  • CVE-2026-99093 mm: don't schedule deferred kernel page table freeing while booting 11h
  • CVE-2026-99095 drm/vc4: drain the hangcheck timer and works on V3D unbind 11h
  • CVE-2026-99096 io_uring/register: don't exempt disabled rings from task restrictions 11h
  • CVE-2026-99097 tee: shm: reject zero-sized allocations in tee_dyn_shm_alloc_helper() 11h
  • CVE-2026-99098 dm-integrity: fix buffer overflow in inline mode with large tag size 11h

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-2026-80808 is "ext4: stop retrying saturated xattr cache entries", 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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