CVE-2026-46033
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
A vulnerability in the Linux kernel's authencesn cryptographic mechanism allows using an undersized hash digest (1-3 bytes) during instance creation, leading to an out-of-bounds memory access when handling the ESN sequence number.
Risk Assessment
An attacker could exploit this via the AF_ALG interface to trigger out-of-bounds read or write, potentially compromising data confidentiality or causing system crashes.
Recommendation
Immediately update the Linux kernel to a version that rejects authencesn instances with invalid hash digest sizes (1-3 bytes).
Original NVD description (English source)
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.