CVE-2026-31610 (GCVE-0-2026-31610)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-04-27 13:56
VLAI?
Title
ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc The kernel ASN.1 BER decoder calls action callbacks incrementally as it walks the input. When ksmbd_decode_negTokenInit() reaches the mechToken [2] OCTET STRING element, ksmbd_neg_token_alloc() allocates conn->mechToken immediately via kmemdup_nul(). If a later element in the same blob is malformed, then the decoder will return nonzero after the allocation is already live. This could happen if mechListMIC [3] overrunse the enclosing SEQUENCE. decode_negotiation_token() then sets conn->use_spnego = false because both the negTokenInit and negTokenTarg grammars failed. The cleanup at the bottom of smb2_sess_setup() is gated on use_spnego: if (conn->use_spnego && conn->mechToken) { kfree(conn->mechToken); conn->mechToken = NULL; } so the kfree is skipped, causing the mechToken to never be freed. This codepath is reachable pre-authentication, so untrusted clients can cause slow memory leaks on a server without even being properly authenticated. Fix this up by not checking check for use_spnego, as it's not required, so the memory will always be properly freed. At the same time, always free the memory in ksmbd_conn_free() incase some other failure path forgot to free it.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < 745a535461bbb90a56d9357573c9f97a5c12abe1 (git)
Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < dd577cb55588ec3fbc66af3621280306601c4192 (git)
Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < dd53414e301beb915fe672dc4c4a51bafb917604 (git)
Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < 269c800a7a7e363459291885b35f7bc72e231ed6 (git)
Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < 6c8c44e6553b9f072f62d9875e567766eb293162 (git)
Affected: fad4161b5cd01a24202234976ebbb133f7adc0b5 , < ad0057fb91218914d6c98268718ceb9d59b388e1 (git)
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    Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.83 , ≤ 6.12.* (semver)
Unaffected: 6.18.24 , ≤ 6.18.* (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0.1 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)
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}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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