Linux Kernel up to 7.1.8 sockmap tcp_bpf_sendmsg_redir use after free

CVSS Meta Temp Score
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CTI Interest Score
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9.5$5k-$25k1.34

Summaryinfo

A vulnerability has been found in Linux Kernel up to 7.1.8 and classified as very critical. Affected by this vulnerability is the function tcp_bpf_sendmsg_redir of the component sockmap. Performing a manipulation results in use after free. This vulnerability was named CVE-2026-74589. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 7.1.8. This affects the function tcp_bpf_sendmsg_redir of the component sockmap. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In 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.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-74589 since 08/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/22/2026).

Upgrading to version 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, 6.18.45 or 7.1.9 eliminates this vulnerability. Applying the patch 41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf/9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3/90a19b0894ba79a699b48cf44421b36fbd566e99/d192cff2a37d59206dabe6ec2e60ceac6271f274/4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf/a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10/1cec526cf0a2227395f2c2f4b671cb052ff0b00e/a76624733730e541e4955fdecf506af2f6b20558 is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.265/5.15.216/6.1.183/6.6.152/6.12.104/6.18.45/7.1.9
Patch: 41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf/9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3/90a19b0894ba79a699b48cf44421b36fbd566e99/d192cff2a37d59206dabe6ec2e60ceac6271f274/4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf/a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10/1cec526cf0a2227395f2c2f4b671cb052ff0b00e/a76624733730e541e4955fdecf506af2f6b20558

Timelineinfo

08/15/2026 CVE reserved
08/22/2026 +7 days Advisory disclosed
08/22/2026 +0 days VulDB entry created
08/22/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74589 (🔒)
GCVE (CVE): GCVE-0-2026-74589
GCVE (VulDB): GCVE-100-394383

Entryinfo

Created: 08/22/2026 18:01
Changes: 08/22/2026 18:01 (59)
Complete: 🔍
Cache ID: 216::103

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