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Out-of-bounds Read Affecting kernel-rt-64k-debug package, versions *

Severity

 Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.73% (52nd percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRT64KDEBUG-18992233
  • published20 Aug 2026
  • disclosed15 Aug 2026
Report a new vulnerability Found a mistake?

Introduced: 15 Aug 2026

NewCVE-2026-72466  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-64k-debug.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-debug package and not the kernel-rt-64k-debug package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

xprtrdma: Fix bcall rep leak and unbounded peek

rpcrdma_is_bcall() decodes a reply's first words to decide whether the frame is a backchannel call. Two issues in that decode path let a short or malformed reply leak the receive buffer and drain the Receive queue.

First, the speculative peek

p = xdr_inline_decode(xdr, 0);
/* five p++ reads follow */

asks xdr_inline_decode() for zero bytes, which returns xdr->p without consulting xdr->end. The five subsequent __be32 reads can then walk up to 20 bytes past the wire payload into stale regbuf contents and misclassify the reply as a backchannel call.

Second, after the post-peek

p = xdr_inline_decode(xdr, 3 * sizeof(*p));
if (unlikely(!p))
        return true;

the short-header arm returns true without calling rpcrdma_bc_receive_call(). The contract with the caller is that a true return transfers ownership of rep to the backchannel path:

rpcrdma_reply_handler()
  if (rpcrdma_is_bcall(r_xprt, rep))
          return;        /* bare return, skips out_post */
  ...
out_post:
  rpcrdma_post_recvs(r_xprt, credits + ...);

Because rpcrdma_bc_receive_call() never ran, no one took rep, but rpcrdma_reply_handler still bare-returns past rpcrdma_rep_put() and rpcrdma_post_recvs(). The rep, with its persistently DMA-mapped receive buffer, is orphaned on rb_all_reps and freed only at transport teardown. This completion reposts nothing, so its slot is reclaimed only when a later forward-channel reply reaches out_post and rpcrdma_post_recvs() allocates a fresh rep to backfill; absent that traffic the Receive queue drains and the peer's Sends draw RNR NAKs.

Fix by consulting xdr->end after the zero-length peek so the five __be32 reads cannot run unless 20 bytes of wire payload remain. A byte-precise comparison against xdr->end is required because a non-4-aligned receive rounds the stream's word count up past the true payload. Also return false from the short-header arm so the reply falls through the normal out_norqst cleanup chain (rpcrdma_rep_put() plus rpcrdma_post_recvs()).

CVSS Base Scores

version 3.1