CVE Hub
CVE-2026-99083
ksmbd: fix heap out-of-bounds write in krb5_authenticate()
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CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack conditions and impact
Derived from the CNA (via NVD) CVSS 3.1 vector| Metric | Value | Meaning |
|---|---|---|
| Attack vector AV | N | Network |
| Attack complexity AC | L | Low (easy) |
| Privileges required PR | L | Regular user |
| User interaction UI | N | None |
| Scope S | U | Unchanged |
| Confidentiality C | H | High |
| Integrity I | H | High |
| Availability A | H | High |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
CVSS assessments
| Provider | Version | Score | Vector |
|---|---|---|---|
| NVD / 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary) | 3.1 | 8.8 HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CNA / Linux | 3.1 | 8.8 HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products and packages
CNA (CVE.org)
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 … < 59c6dcc5dd9dafe764ca0d40525933b2be69b059 affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 … < 80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 … < 517404e157395d0f8da125ca956c566895dfcd06 affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 … < 4722d06b2907585074252061b1024a696c1cfc23 affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 … < 23a0be6a84a38ac169eeab49017934e8e27c65f0 affected: 0 … < 6.6.160 affected: 0 … < 6.12.114 affected: 0 … < 6.18.58 affected: 0 … < 7.2.12 default: unaffected |
| Linux | Linux | 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 … <= * default: affected |
Open-source packages (GitHub Advisory / OSV)
ksmbd: fix heap out-of-bounds write in krb5_authenticate()
| Ecosystem | Package | Affected versions | Fixed in |
|---|---|---|---|
| >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 59c6dcc5dd9dafe764ca0d40525933b2be69b059; < 80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a; < 517404e157395d0f8da125ca956c566895dfcd06; < 4722d06b2907585074252061b1024a696c1cfc23; < 23a0be6a84a38ac169eeab49017934e8e27c65f0; < 6.6.160; < 6.12.114; < 6.18.58; < 7.2.12 v7.2.11, v6.18.57, v6.12.113, v6.6.159, v6.6.158, v7.2.10, v6.18.56, v6.12.112, v7.2.9, v6.18.55, v7.2.8, v6.18.54, v6.12.111, v6.6.157, v7.2, v7.2.7, v6.18.53, v7.2.6, v6.18.52, v6.12.110, … (+1244) | 59c6dcc5dd9dafe764ca0d40525933b2be69b059, 80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a, 517404e157395d0f8da125ca956c566895dfcd06, 4722d06b2907585074252061b1024a696c1cfc23, 23a0be6a84a38ac169eeab49017934e8e27c65f0, 6.6.160, 6.12.114, 6.18.58, 7.2.12 | ||
| Linux | Kernel | < 6.6.160; >= 6.7.0, < 6.12.114; >= 6.13.0, < 6.18.58; >= 6.19.0, < 7.2.12 | 6.6.160, 6.12.114, 6.18.58, 7.2.12 |
Linux distribution status
References (8)
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git OSV
- https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0 NVD, CNA, OSV
- https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23 NVD, CNA, OSV
- https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06 NVD, CNA, OSV
- https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059 NVD, CNA, OSV
- https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a NVD, CNA, OSV
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99083.json OSV
- https://nvd.nist.gov/vuln/detail/CVE-2026-99083 OSV