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VulnerabilityPublished Updated

CVE-2026-102272: Hermes agent · PyJWT BOM Bypass

Affects hermes-agentSource GCVE Database

0

Mentioned vulnerabilities

Authoritative record:CVE-2026-102272· High 7.4

Not known to be exploited · CVSS 7.4 High : upgrade to 0.22.4 soon.

Data as of 27 Oct 2026, 21:00 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.22.4
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade hermes-agent to 0.22.4.

Affected software

ProductAffectedFixed in
Homebrewhermes-agentpkg:brew/hermes-agentOther threatsAffected
  • >=0.21.6 <0.22.4
  • >=2026.7.1 <=2026.9.24
Fixed in
  • 0.22.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been committed to PyJWT that correctly handles UTF-8 BOM prefixes and uses JSON parsing to detect asymmetric keys, preventing this bypass. Users should upgrade to PyJWT version 0.22.4 or later where the fix is included. If you cannot patch yet, users should avoid configurations that accept both HS256 and RS256 algorithms simultaneously or implement additional validation to reject BOM-prefixed keys. No other mitigations are indicated by the vendor advisory.

Description

PyJWT version 2.13.0 contains a vulnerability where a UTF-8 BOM prefix in a JSON Web Key (JWK) bypasses a key validation guard, allowing an attacker to use an RSA public key as an HMAC secret. This enables forging JWT tokens with arbitrary claims when the verifier accepts both HS256 and RS256 algorithms. The vulnerability leads to complete authentication and authorization bypass. A fix has been committed but not yet released.

References

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