CVE-2026-46033
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Out-of-Bounds Access in Linux Kernel crypto_authenc_esn

Publication date: 2026-05-27

Last updated on: 2026-06-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: crypto: authencesn - reject short ahash digests during instance creation authencesn requires either a zero authsize or an authsize of at least 4 bytes because the ESN encrypt/decrypt paths always move 4 bytes of high-order sequence number data at the end of the authenticated data. While crypto_authenc_esn_setauthsize() already rejects explicit non-zero authsizes in the range 1..3, crypto_authenc_esn_create() still copied auth->digestsize into inst->alg.maxauthsize without validating it. The AEAD core then initialized the tfm's default authsize from that value. As a result, selecting an ahash with digest size 1..3, such as cbcmac(cipher_null), exposed authencesn instances whose default authsize was invalid even though setauthsize() would have rejected the same value. AF_ALG could then trigger the ESN tail handling with a too-short tag and hit an out-of-bounds access. Reject authencesn instances whose ahash digest size is in the invalid non-zero range 1..3 so that no tfm can inherit an unsupported default authsize.
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Meta Information
Published
2026-05-27
Last Modified
2026-06-16
Generated
2026-06-16
AI Q&A
2026-05-27
EPSS Evaluated
2026-06-15
NVD
CVE-2026-46033
EUVD
EUVD-2026-32414
Affected Vendors & Products
Showing 8 associated CPEs
Vendor Product Version / Range
linux linux_kernel 7.1
linux linux_kernel From 6.7 (inc) to 6.12.86 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.175 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.209 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.140 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.27 (exc)
linux linux_kernel From 6.19 (inc) to 7.0.4 (exc)
linux linux_kernel From 4.11 (inc) to 5.10.258 (exc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.
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Executive Summary

This vulnerability exists in the Linux kernel's crypto authentication mechanism called authencesn. The issue arises because authencesn requires an authentication size (authsize) of either zero or at least 4 bytes, due to how it processes sequence number data.

However, during instance creation, the code failed to properly validate the authsize value copied from the digest size of the authentication hash (ahash). Specifically, it allowed digest sizes of 1 to 3 bytes, which are invalid.

This improper validation could lead to the use of a too-short authentication tag, causing out-of-bounds memory access when the ESN tail handling is triggered. The vulnerability was fixed by rejecting authencesn instances with ahash digest sizes in the invalid range of 1 to 3 bytes.

Impact Analysis

This vulnerability can lead to out-of-bounds memory access in the Linux kernel's cryptographic authentication code. Such memory access issues can cause system instability, crashes, or potentially allow attackers to execute arbitrary code or cause denial of service.

If an attacker can trigger this vulnerability, they might exploit it to compromise system security or reliability, especially in systems relying on the affected crypto authentication mechanisms.

Mitigation Strategies

The vulnerability has been resolved in the Linux kernel by rejecting authencesn instances whose ahash digest size is in the invalid non-zero range 1 to 3.

To mitigate this vulnerability, you should update your Linux kernel to a version that includes this fix.

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