CVE-2026-99083ksmbd: fix heap out-of-bounds write in krb5_authenticate()
- 8.8HighCVSS base score
- 0.45%Exploitation in 30 daysEPSS · top 61% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix heap out-of-bounds write in krb5_authenticate() In krb5_authenticate(), out_len is calculated to determine available headroom in response_buf for the incoming Kerberos AP-REP token. However, when SMB2_SESSION_SETUP is processed as a non-first element of a compounded SMB2 request, the calculation omits work->next_smb2_rsp_hdr_off. This causes out_len to overstate remaining buffer headroom by the cumulative size of prior responses in the compound chain. Consequently, the length check in ksmbd_krb5_authenticate() (*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy() to write the AP-REP blob past the end of response_buf into adjacent kernel heap memory. Fix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len, ensuring it accurately reflects physical remaining buffer space.
Timeline
ID reserved
By Linux
- 28 days later
· 28 days later
Published
- 7 days later
· 7 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.45% · top 61% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.
Affected products
- affected 676392184785ace61e939831e7ca44a03d438c3b – < a07dfb33112a42437f9d2d0bfd35c68575257381
- affected ef572ffa8eb44111eed2925fbb2adca78bdcbf61 – < 1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff
- affected 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 – < 59c6dcc5dd9dafe764ca0d40525933b2be69b059
- affected 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 – < 80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a
- affected 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 – < 517404e157395d0f8da125ca956c566895dfcd06
- affected 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 – < 4722d06b2907585074252061b1024a696c1cfc23
- affected 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 – < 23a0be6a84a38ac169eeab49017934e8e27c65f0
- affected 2ba03cecb12ac7ac9e0170e251543c56832d9959
- affected 5.15.145 – < 5.15.224
- affected 6.1.40 – < 6.1.191
- affected 6.4.5 – < 6.5
- affected 6.5
- unaffected < 6.5
- unaffected 5.15.224 – ≤ 5.15.*
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.160 – ≤ 6.6.*
- unaffected 6.12.114 – ≤ 6.12.*
- unaffected 6.18.58 – ≤ 6.18.*
- unaffected 7.2.12 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/a07dfb33112a42437f9d2d0bfd35c68575257381 (opens in a new tab)
- https://git.kernel.org/stable/c/1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff (opens in a new tab)
- https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059 (opens in a new tab)
- https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a (opens in a new tab)
- https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06 (opens in a new tab)
- https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23 (opens in a new tab)
- https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-108934 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-99083)Record last updated .