Cyber Resilience

CVE-2026-9537

Published
17 July 2026
Modified
20 July 2026
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS Score 0.0023 14th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-9537 is a medium-severity Observable Timing Discrepancy (CWE-208) vulnerability. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Forge Web Credentials (T1606); ranked at the 14th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison. The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time…

more

varies with the number of matching leading bytes. A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.

CWE(s)
CWE-208

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1606 Forge Web Credentials Credential Access
Adversaries may forge credential materials that can be used to gain access to web applications or Internet services.
attack.mitre.org →
Why these techniques?

Non-constant-time HMAC comparison (CWE-208) directly enables remote timing attack to recover secret and forge valid JWT tokens (T1606).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1606 Forge Web Credentials Credential Accessconfidence: HIGH
Timing attack on HMAC verification directly enables recovery of the signing secret to forge valid JWT tokens.
attack.mitre.org →
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-44368Shared CWE-208
CVE-2025-52457Shared CWE-208
CVE-2026-27882Shared CWE-208
CVE-2026-6656Shared CWE-208
CVE-2025-59058Shared CWE-208
CVE-2026-33129Shared CWE-208
CVE-2026-40194Shared CWE-208
CVE-2025-22234Shared CWE-208
CVE-2026-28464Shared CWE-208
CVE-2024-41828Shared CWE-208

Affected Assets

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JWT
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

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Detect
Catch it (NIST detect / respond)

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Harden
Shrink the surface (DISA STIG)

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Validate
Prove the fix (OWASP ASVS)
  • V11.2.4

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-30 Concealment and Misdirection
addresses: CWE-208

Timing randomization or delays can mask true operation timing and mislead timing-based attacks.

SC-31 Covert Channel Analysis
addresses: CWE-208

Observable timing discrepancies are a primary mechanism for constructing covert timing channels; analysis identifies and bounds them, limiting exploitation.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require constant-time implementations that eliminate observable timing discrepancies.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.17 Clock synchronization none match
none

Consistent reference clocks limit the attacker's ability to measure or manipulate timing differences that could reveal internal state or processing paths.

References