CVE-2026-13758 Other in CryptX
Timing side-channel in CryptX allows attackers to forge AEAD messages by recovering authentication tags byte-by-byte.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-13758?
CVE-2026-13758 is a low-severity vulnerability in MIK CryptX, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path.
The decrypt_done($tag) form compares it against the computed tag with memNE (memcmp() != 0), which short-circuits on the first differing byte, so its run time depends on the number of matching leading bytes. This affects all five AEAD modes: GCM, CCM, ChaCha20Poly1305, EAX and OCB. The one-shot *_decrypt_verify helpers are unaffected; they verify the tag inside libtomcrypt with a constant-time comparison.
The timing difference is a tag-verification oracle. An attacker who can submit many candidate tags for the same nonce, ciphertext and associated data while measuring the timing precisely enough may recover the expected tag byte by byte and forge a message that verifies.
Weakness: CWE-208
Which versions are affected by CVE-2026-13758?
How do I fix CVE-2026-13758?
Upgrade to a fixed version.
Is CVE-2026-13758 being exploited?
There is no known exploitation of CVE-2026-13758 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-13758, GHSA-55gr-9963-833c, UBUNTU-CVE-2026-13758.