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Vulnerabilities

Vulnerability · CVE-2026-99083

CVE-2026-99083: ksmbd: fix heap out-of-bounds write in krb5_authenticate()

Published Oct 23, 2026 · catalog updated Oct 23, 2026 · Linux Linux Kernel

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-99083. EPSS is 0.45%. Act only if a listed version of Linux Linux Kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.45%
Remediation
Advisory link
Affected products
Debian:12 linux · Debian:13 linux · Debian:14 linux · linux kernel · vendor Linux Linux

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 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 linux6.1.106-1, 6.1.106-2, 6.1.106-3
  • Debian:13 linux6.12.100-1, 6.12.101-1, 6.12.105-1
  • Debian:14 linux6.12.100-1, 6.12.101-1, 6.12.105-1
  • linux kernelversion unspecified
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-99083

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-99083. EPSS is 0.45%. Act only if a listed version of Linux Linux Kernel is installed.

Which versions are affected?

Compare what you have installed with 6.1.106-1, 6.1.106-2, 6.1.106-3, 6.12.100-1, 6.12.101-1, 6.12.105-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.45%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Linux Kernel CVE

    Detected

    From: Greg Kroah-Hartman 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

  2. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    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_rs

Sources

  • CVE.orgVulnerability recordCVE-2026-99083

    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_

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-99083

    30-day exploitation probability 0.45%

    first.org
  • Linux Kernel CVEVendor advisoryCVE-2026-99083

    From: Greg Kroah-Hartman 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 in

    git.kernel.org
  • OpenCVEVendor advisoryCVE-2026-99083

    CVE-2026-99083 is named on the public OpenCVE page.

    opencve.io
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2026-99083
    osv.dev
  • Tenable CVE DatabaseVulnerability recordCVE-2026-99083

    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_rs

    tenable.com
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-99083
    osv.dev

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 31, 2026
  • Linux Kernel CVEOct 28, 2026
  • Tenable CVE DatabaseOct 25, 2026
  • OpenCVEOct 24, 2026
  • Trivy Vulnerability DBOct 23, 2026
  • OpenSSF OSV / OSV ScannerOct 23, 2026
  • CVE.orgOct 23, 2026