CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decrypt_done path

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Summary

CVECVE-2026-13758
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-29 21:16:43 UTC
Updated2026-06-30 14:16:25 UTC
DescriptionCryptX 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.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS: 0.002950000 probability, percentile 0.212230000 (date 2026-07-04)

Problem Types: CWE-208 | CWE-208 CWE-208 Observable Timing Discrepancy

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA MIK CryptX affected 0.088_001 custom Not specified

References

ReferenceSourceLinkTags
metacpan.org/release/MIK/CryptX-0.088_001/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
www.openwall.com/lists/oss-security/2026/06/29/19 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/DCIT/perl-CryptX/commit/7e56347d420aaf43b2ee1586f4a230492ccf1... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: Upgrade to CryptX 0.088_001 or later.

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