# CVE-2026-13758: Other in CryptX

> Timing side-channel in CryptX allows attackers to forge AEAD messages by recovering authentication tags byte-by-byte.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Jun 2026
- **Updated:** 30 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-13758, GHSA-55gr-9963-833c, UBUNTU-CVE-2026-13758

## 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 (Observable Timing Discrepancy)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13758 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-13758 in the wild and no public exploit code.

Affected product: MIK CryptX. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-13758/ (Markdown: https://insights.sbomify.com/CVE-2026-13758/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13758
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13758
- OSV: https://osv.dev/vulnerability/CVE-2026-13758

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-13758/
Summaries are generated and may contain mistakes; the official description above is the record.