# CVE-2026-13758: libcryptx-perl: CryptX versions before 0.088_001 for Perl compare AEAD authentication tags in non-constant time in the streaming decr...

CVE-2026-13758 is fixed in 5 products on 1 platform, first by ALAS2023-2026-1834, released June 11, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-13758
- Priority: Routine
- CVSS: 3.7 (low)
- EPSS: 0.0040
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 11, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libcryptx-perl Debian 14 | 0.089-1 | [DEBIAN-CVE-2026-13758](https://patchblox.com/security/data/fix/linux/debian-cve-2026-13758.md) | Jun 30, 2026 |
| Linux | perl-CryptX amzn 2023 | 0.088-2.amzn2023.0.3 | [ALAS2023-2026-1834](https://patchblox.com/security/data/fix/linux/alas2023-2026-1834.md) | Jun 11, 2026 |
| Linux | perl-CryptX-debuginfo amzn 2023 | 0.088-2.amzn2023.0.3 | [ALAS2023-2026-1834](https://patchblox.com/security/data/fix/linux/alas2023-2026-1834.md) | Jun 11, 2026 |
| Linux | perl-CryptX-debugsource amzn 2023 | 0.088-2.amzn2023.0.3 | [ALAS2023-2026-1834](https://patchblox.com/security/data/fix/linux/alas2023-2026-1834.md) | Jun 11, 2026 |
| Linux | perl-CryptX-tests amzn 2023 | 0.088-2.amzn2023.0.3 | [ALAS2023-2026-1834](https://patchblox.com/security/data/fix/linux/alas2023-2026-1834.md) | Jun 11, 2026 |

---

Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.