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CVE-2026-98171

HIGH 8.8

Published 2026-10-06 · Last modified 2026-10-19

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs Fix several related bounds checking and pointer lifecycle issues in receive_encrypted_standard()'s handling of compound encrypted frames: - Clear next_buffer after assigning it to server->bigbuf. A stale next_buffer pointer can lead to a use-after-free on subsequent error paths. - Update pdu_length to the decrypted plaintext size (buf_size). Using the pre-decryption length allows NextCommand to point into stale ciphertext residue. - Reject next_cmd values smaller than MID_HEADER_SIZE(server). - Fix an integer overflow in the upper bound check by verifying pdu_length - next_cmd < MID_HEADER_SIZE(server), ensuring the trailing slice is large enough for a header.

ELEVATED IMPACT

Severe if exploited (CVSS 8.8), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.5%chance of exploitation in 30 days · 43rd percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

8.8CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: A user must take an action (click / open a file)
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors Linux

Products Linux

Weakness (CWE)

Not classified.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References and research data (JSON)

All CVSS metrics

  • HIGH 8.8 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  • HIGH 8.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS