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.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-13758)

Note that Nessus relies on the presence of the package as reported by the vendor.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1834 advisory.

    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. (CVE-2026-13758)

    CryptX versions before 0.088_001 for Perl have a stack buffer overflow in four AEAD decrypt_verify     helpers.

    The gcm_decrypt_verify, ccm_decrypt_verify, chacha20poly1305_decrypt_verify and eax_decrypt_verify XS     routines copied the caller-supplied authentication tag into a fixed 144-byte stack buffer (MAXBLOCKSIZE)     without checking the supplied length. A longer tag overwrites the stack past the buffer. Version 0.088     added the clamp to gcm_decrypt_verify, and 0.088_001 added it to the other three.

    Any caller of an affected helper that forwards an attacker-controlled tag longer than the buffer can     trigger the overflow. (CVE-2026-41565)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Type	Severity
323881	Linux Distros Unpatched Vulnerability : CVE-2026-13758	Nessus	Misc.	Local	low
322012	Amazon Linux 2023 : perl-CryptX, perl-CryptX-tests (ALAS2023-2026-1834)	Nessus	Amazon Linux Local Security Checks	Local	low

Detections

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CVE-2026-13758

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Tenable Plugins

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low