Critical severity · published Apr 23, 2026
CVE-2026-31533
net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
9.8
CVSS
0.4%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
The -EBUSY handling in tls_do_encryption(), introduced by commit
859054147318 ("net: tls: handle backlogging of crypto requests"), has
a use-after-free due to double cleanup of encrypt_pending and the
scatterlist entry.
When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to
the cryptd backlog and the async callback tls_encrypt_done() will be
invoked upon completion. That callback unconditionally restores the
scatterlist entry (sge->offset, sge->length) and decrements
ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an
error, the synchronous error path in tls_do_encryption() performs the
same cleanup again, double-decrementing encrypt_pending and
double-restoring the scatterlist.
The double-decrement corrupts the encrypt_pending sentinel (initialized
to 1), making tls_encrypt_async_wait() permanently skip the wait for
pending async callbacks. A subsequent sendmsg can then free the
tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still
pending, resulting in a use-after-free when the callback fires on the
freed record.
Fix this by skipping the synchronous cleanup when the -EBUSY async
wait returns an error, since the callback has already handled
encrypt_pending and sge restoration.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.15.160 before 5.15.203; 6.1.84 before 6.1.169; 6.6.18 before 6.6.135; 6.7.6 before 6.8; 6.8.1 before 6.12.82; 6.13 before 6.18.23; +8 more · source: NVD
LI
Linux · Linux
3ade391adc584f17b5570fd205de3ad029090368 before 414fc5e5a5aff776c150f1b86770e0a25a35df3a; cd1bbca03f3c1d845ce274c0d0a66de8e5929f72 before 02f3ecadb23558bbe068e6504118f1b712d4ece0; 13eca403876bbea3716e82cdfe6f1e6febb38754 before 0e43e0a3c94044acc74b8e0927c27972eb5a59e8; 8590541473188741055d27b955db0777569438e3 before aa9facde6c5005205874c37db3fd25799d741baf; 8590541473188741055d27b955db0777569438e3 before 5d70eb25b41e9b010828cd12818b06a0c3b04412; 8590541473188741055d27b955db0777569438e3 before 2694d408b0e595024e0fc1d64ff9db0358580f74; +7 more · source: vendor
SS
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7; V3.1.6; V3.1.5; V3.1.7 · source: CISA
SS
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7; V3.1.6; V3.1.5; V3.1.7 · source: CISA
SS
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP · Siemens
V3.1.6; V3.1.5; V3.1.7 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-31533
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-31533
Patch
https://git.kernel.org/stable/c/02f3ecadb23558bbe068e6504118f1b712d4ece0
Patch
https://git.kernel.org/stable/c/0e43e0a3c94044acc74b8e0927c27972eb5a59e8
Patch
https://git.kernel.org/stable/c/2694d408b0e595024e0fc1d64ff9db0358580f74
Patch
https://git.kernel.org/stable/c/414fc5e5a5aff776c150f1b86770e0a25a35df3a
Patch
https://git.kernel.org/stable/c/5d70eb25b41e9b010828cd12818b06a0c3b04412
Patch
https://git.kernel.org/stable/c/a9b8b18364fffce4c451e6f6fd218fa4ab646705
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