Bug 2540182 (CVE-2026-93207) - CVE-2026-93207 kernel: SUNRPC: Zero rpc_gss_wire_cred at svcauth_gss_decode_credbody() entry
Summary: CVE-2026-93207 kernel: SUNRPC: Zero rpc_gss_wire_cred at svcauth_gss_decode_c...
Keywords:
Status: NEW
Alias: CVE-2026-93207
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-24 15:21 UTC by OSIDB Bzimport
Modified: 2026-10-01 21:20 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2026-09-24 15:21:55 UTC
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.


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