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VulnerabilityPublished Updated

CVE-2026-102273: Hermes agent · PyJWT accepts public JWK containers as HMAC secrets

Affects hermes-agentSource GCVE Database

0
Authoritative record:CVE-2026-102273· High 7.4

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

Data as of 27 Oct 2026, 20:59 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

Upgrade to PyJWT version 2.14.0 or later, which includes the official fix rejecting public JWK containers as HMAC keys. Applications should also ensure they do not mix symmetric and asymmetric algorithms in the same verification path and avoid passing raw public JWK/JWKS JSON as HMAC secrets. The fix is confirmed and tested; no additional mitigation steps are required beyond applying the update.

Description

PyJWT version 2.13.0 has a vulnerability involving algorithm confusion where public JWK containers can be incorrectly accepted as HMAC secrets. This allows an attacker who knows the public key material to forge HS256/HS384/HS512 JWT tokens if the application mixes symmetric and asymmetric algorithms and uses raw public JWK/JWKS JSON as the HMAC secret. The issue is fixed in PyJWT 2.14.0.

References

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