CVE-2026-80808: linux
Vulnerability summary
CVE-2026-80808 is a vulnerability in linux with no CVSS score yet. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.7% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 2 · Related 1Timeline
- 04-09-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
Risk metrics not yet published.
EPSS trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
0.00 pp
From 0.19% on 22-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Ubuntu165 products
- linuxAll versions (No fix recorded)
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded)
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.187-1 | < 6.12.107-1 | < 7.1.12-1
- linux-6.12< 6.12.107-1~deb12u1
Linux1 product
- linux≥ 1a56cd972ce121b6cf2517a47a578782bbd2ec95, < 119a2f053242ed75bdd2ebc95baf3ae7db6ccacf | ≥ 1be97463696c7291a3e1547614e96432b0bd3add, < 61631352a5b405c89be579de00903b72e6888aa4 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < 8865cd664484517703df5c18a965dc3227572b87 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < a40c45268f4358207aa9c53764fed2e05f62986a | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < 889ec86464d261f026f6c334040cfc6c58c99d58 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < 4902a5cba21aeaf91e6b29e20e0967a5f6abdcd9 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < 55ee6533c1db7f7656fa8dd19637f3f8b8c08dc5 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < dbd4aea175ad3c46436acb251e817b4374628072 | ≥ 65f8b80053a1b2fd602daa6814e62d6fa90e5e9b, < 54b6bd40898de7906acb2bccc9a96d1b8e6b4323 | 98953044b3cdb2cb7d82e7365b659e2ed4f4ca4d | af8ecc8d20e72130771cc076bce7fcf17ccda6c4 | c6fac5cf5a5098732623bcd00a8a3eb9f5465144 | 96fa141fa295ae9428da73c56c9852053b575c04 | ≥ 5.10.163, < 5.10.267 | ≥ 5.15.61, < 5.15.218 | ≥ 4.19.270, < 4.20 | ≥ 5.4.229, < 5.5 | ≥ 5.18.18, < 5.19 | ≥ 5.19.2, < 5.20 | 6.0
3 vendors · 168 products
