bpf, sockmap: Fix sk_redir use-after-free in send verdict

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74589
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:31 UTC
Updated2026-08-25 06:18:33 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix sk_redir use-after-free in send verdict sk_psock_msg_verdict() takes a socket reference for psock->sk_redir. tcp_bpf_send_verdict() copies that pointer while holding the source socket lock, but does not take a reference for the local copy before dropping the lock around tcp_bpf_sendmsg_redir(). When apply_bytes keeps the cached verdict active, another sendmsg() on the same source socket can consume the remaining bytes and release the cached reference while the first thread still holds only the raw local pointer: CPU 0 CPU 1 sk_redir = psock->sk_redir apply_bytes remains nonzero release_sock(sk) lock_sock(sk) apply_bytes reaches zero psock->sk_redir = NULL release_sock(sk) tcp_bpf_sendmsg_redir(sk_redir) sock_put(sk_redir) tcp_bpf_sendmsg_redir(sk_redir) The final sock_put() can free sk_redir before CPU 0 dereferences it. KASAN reported: BUG: KASAN: slab-use-after-free in tcp_bpf_sendmsg_redir+0xf39/0x1020 Read of size 8 at addr ffff888108537090 by task poc/87 Call Trace: tcp_bpf_sendmsg_redir+0xf39/0x1020 tcp_bpf_sendmsg+0x977/0x1a50 __sys_sendto+0x32c/0x3a0 __x64_sys_sendto+0xdb/0x1b0 Allocated by task 85: sk_prot_alloc+0x56/0x210 sk_clone+0x6f/0x14b0 inet_csk_clone_lock+0x24/0x740 tcp_create_openreq_child+0x25/0x2710 tcp_v4_syn_recv_sock+0x10a/0xe00 Freed by task 0: __kasan_slab_free+0x43/0x70 slab_free_after_rcu_debug+0xa6/0x1e0 rcu_core+0x50a/0x1850 Last potentially related work creation: __sk_destruct+0x3da/0x540 sk_psock_destroy+0x81e/0xab0 process_one_work+0x63a/0x1070 Take a temporary socket reference while the source socket lock still protects psock->sk_redir, and drop it after tcp_bpf_sendmsg_redir() returns. This keeps each unlocked use independent of cached-verdict ownership.

Risk And Classification

Primary CVSS: v3.1 8.4 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001770000 probability, percentile 0.072130000 (date 2026-08-24)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c 41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c 9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3 git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c 90a19b0894ba79a699b48cf44421b36fbd566e99 git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c d192cff2a37d59206dabe6ec2e60ceac6271f274 git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c 4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10 git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c 1cec526cf0a2227395f2c2f4b671cb052ff0b00e git Not specified
CNA Linux Linux affected 604326b41a6fb9b4a78b6179335decee0365cd8c a76624733730e541e4955fdecf506af2f6b20558 git Not specified
CNA Linux Linux affected 4.20 Not specified
CNA Linux Linux unaffected 4.20 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/90a19b0894ba79a699b48cf44421b36fbd566e99 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1cec526cf0a2227395f2c2f4b671cb052ff0b00e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d192cff2a37d59206dabe6ec2e60ceac6271f274 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a76624733730e541e4955fdecf506af2f6b20558 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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