Linux Kernel up to 6.19.12 tls tls_do_encryption use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.19.12. It has been declared as critical. Affected by this issue is the function tls_do_encryption of the component tls. Such manipulation leads to use after free. This vulnerability is uniquely identified as CVE-2026-31533. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.12. It has been rated as critical. Affected by this issue is the function tls_do_encryption of the component tls. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-31533 since 03/09/2026. The exploitation is known to be easy. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 06/18/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310043 (Linux Distros Unpatched Vulnerability : CVE-2026-31533), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.203, 6.1.169, 6.6.135, 6.12.82, 6.18.23 or 6.19.13 eliminates this vulnerability. Applying the patch 414fc5e5a5aff776c150f1b86770e0a25a35df3a/0e43e0a3c94044acc74b8e0927c27972eb5a59e8/aa9facde6c5005205874c37db3fd25799d741baf/5d70eb25b41e9b010828cd12818b06a0c3b04412/2694d408b0e595024e0fc1d64ff9db0358580f74/a9b8b18364fffce4c451e6f6fd218fa4ab646705 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (310043) and CERT Bund (WID-SEC-2026-1265). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

  • Debian Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
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: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 310043
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-31533

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.203/6.1.169/6.6.135/6.12.82/6.18.23/6.19.13
Patch: 414fc5e5a5aff776c150f1b86770e0a25a35df3a/0e43e0a3c94044acc74b8e0927c27972eb5a59e8/aa9facde6c5005205874c37db3fd25799d741baf/5d70eb25b41e9b010828cd12818b06a0c3b04412/2694d408b0e595024e0fc1d64ff9db0358580f74/a9b8b18364fffce4c451e6f6fd218fa4ab646705

Timelineinfo

03/09/2026 CVE reserved
04/23/2026 +44 days Advisory disclosed
04/23/2026 +0 days VulDB entry created
06/18/2026 +56 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31533 (🔒)
GCVE (CVE): GCVE-0-2026-31533
GCVE (VulDB): GCVE-100-359162
CERT Bund: WID-SEC-2026-1265 - Linux Kernel: Schwachstelle ermöglicht nicht spezifizierten Angriff

Entryinfo

Created: 04/23/2026 19:51
Updated: 06/18/2026 14:39
Changes: 04/23/2026 19:51 (59), 04/24/2026 08:14 (2), 06/03/2026 08:56 (7), 06/18/2026 14:39 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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