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.
References
Configurations
Configuration 1 (hide)
|
History
13 Oct 2026, 14:05
| Type | Values Removed | Values Added |
|---|---|---|
| First Time |
Linux
Linux linux Kernel |
|
| References | () https://git.kernel.org/stable/c/92170e6afe927ab2792a3f71902845789c8e31b1 - Patch | |
| References | () https://git.kernel.org/stable/c/9902a1058992de5d95656b64a3bd95c077f7ba2c - Patch | |
| References | () https://git.kernel.org/stable/c/a91887a5b6ee4b98dfbf1db657ed2b879430149e - Patch | |
| References | () https://git.kernel.org/stable/c/af2c22ccb1f621aff487ff47a040e38e058541e7 - Patch | |
| References | () https://git.kernel.org/stable/c/c7f945f7da097245a2f8ed7775ce48421047ee96 - Patch | |
| References | () https://git.kernel.org/stable/c/d3019c61799adc21811af4b521f11f3dc77f8e04 - Patch | |
| References | () https://git.kernel.org/stable/c/dd206819f210522579010d889d45a9530bb494bc - Patch | |
| References | () https://git.kernel.org/stable/c/f0fea2b6d5453a11ad11713bbf37561b9b3a7edf - Patch | |
| CPE | cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* |
|
| CWE | CWE-416 |
Information
Published : 2026-07-19 16:17
Updated : 2026-10-19 21:17
NVD link : CVE-2026-64007
Mitre link : CVE-2026-64007
CVE.ORG link : CVE-2026-64007
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free