Expired Pointer Dereference Affecting kernel-zfcpdump-devel-matched package, versions *


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.51% (41st percentile)

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  • Snyk IDSNYK-RHEL10-KERNELZFCPDUMPDEVELMATCHED-18559071
  • published6 Aug 2026
  • disclosed19 Jul 2026

Introduced: 19 Jul 2026

NewCVE-2026-64007  (opens in a new tab)
CWE-825  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:10 kernel-zfcpdump-devel-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-zfcpdump-devel-matched package and not the kernel-zfcpdump-devel-matched package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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

netfilter: synproxy: refresh tcphdr after skb_ensure_writable

synproxy_tstamp_adjust() rewrites the TCP timestamp option in place and then patches the TCP checksum via inet_proto_csum_replace4() on the caller-supplied tcphdr pointer. Both ipv4_synproxy_hook() and ipv6_synproxy_hook() obtain that pointer with skb_header_pointer() before calling in, so it may either alias skb->head directly or point at the caller's on-stack _tcph buffer.

Between obtaining the pointer and using it, the function calls skb_ensure_writable(skb, optend), which on a cloned or non-linear skb invokes pskb_expand_head() and frees the old skb->head. After that point the cached th is stale:

caller (ipv[46]_synproxy_hook)
  th = skb_header_pointer(skb, ..., &_tcph)
  synproxy_tstamp_adjust(skb, protoff, th, ...)
    skb_ensure_writable(skb, optend)
      pskb_expand_head()        /* kfree(old skb->head) */
    ...
    inet_proto_csum_replace4(&th->check, ...)
                                /* writes into freed head, or
                                   into the caller's stack copy
                                   leaving the on-wire checksum
                                   stale */

The option bytes are written through skb->data and are fine; only the checksum update goes through th and so lands in the wrong place. The result is either a write into freed slab memory or a packet leaving with a checksum that does not match its payload.

Fix by re-deriving th from skb->data + protoff immediately after skb_ensure_writable() succeeds, so the subsequent checksum update targets the linear, writable header.

CVSS Base Scores

version 3.1