CVE-2026-64551 is a vulnerability in Linux Kernel
Published on July 27, 2026
sctp: validate STALE_COOKIE cause length before reading staleness
In the Linux kernel, the following vulnerability has been resolved:
sctp: validate STALE_COOKIE cause length before reading staleness
When an ERROR chunk with a STALE_COOKIE cause is received in the
COOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure
of Staleness that follows the cause header:
err = (struct sctp_errhdr *)(chunk->skb->data);
stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err)));
err is the first cause in the chunk, not the STALE_COOKIE cause that
caused the dispatch, and nothing guarantees the staleness field is
present. sctp_walk_errors() only requires a cause to be as long as the
4-byte header, so for a STALE_COOKIE cause of length 4 the read runs
past the cause, and for a minimal ERROR chunk past skb->tail. The value
is echoed to the peer in the Cookie Preservative of the reply INIT,
leaking uninitialized memory.
sctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so
check its length there and pass it to sctp_sf_do_5_2_6_stale(), which
reads that cause instead of the first one. A STALE_COOKIE cause too
short to hold the staleness field is discarded.
The read is reachable by any peer that can drive an association into
COOKIE_ECHOED, including an unprivileged process using a raw SCTP socket
in a user and network namespace.
Products Associated with CVE-2026-64551
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Affected Versions
Linux:- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 6022da37786701df1fc5dd946a6dcba59d5473b1 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 861f884f5471632c731cbbd612a1c072e391a624 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 588706ebaf8cdb4a4161602949eba365514b1db1 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below a257b41ddfe9e327b26581ad2777f04b23ac73f5 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 08a8f2d13f703924316e9aeac863a88ef50990c7 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below ebe0a55d954fa8da383b6192edb8f763dcb002d5 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 1cd23ca80784223fa2204e16203f754da4e821f8 is affected.
- Version 2.6.12 is affected.
- Before 2.6.12 is unaffected.
- Version 5.10.261, <= 5.10.* is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.97, <= 6.12.* is unaffected.
- Version 6.18.40, <= 6.18.* is unaffected.
- Version 7.1.5, <= 7.1.* is unaffected.
- Version 7.2-rc4, <= * is unaffected.