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VulnerabilityPublished

CVE-2026-114616: Omnara · Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

Affects omnaraSource GCVE Database

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Authoritative record:CVE-2026-114616· High 7.4

Not known to be exploited · CVSS 7.4 High · fixed in 1.7.2 : patch omnara soon.

Data as of 30 Oct 2026, 09:14 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.17.4
Patch
Available – fixed in 1.7.2
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 22 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Homebrewomnarapkg:brew/omnaraOther threatsAffected
  • >=1.5.2
Fixed in–

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

AI-suggested

A fix is available in versions after 1.7.2, as the vulnerability is confirmed present in Authlib <= 1.7.2. Users should upgrade to a version that rejects empty HMAC keys or apply a patch that enforces non-empty key validation. Until upgraded, ensure that the key source cannot yield an empty value (e.g., environment variables or configuration defaults should never be empty). The vendor advisory confirms the issue and the fix is known from the newer joserfc library, which rejects empty keys explicitly.

Description

Authlib versions up to 1.7.2 accept an empty HMAC key for JWS/JWT signature verification using HS256, HS384, and HS512 algorithms. This allows attackers to forge tokens with arbitrary claims that pass signature verification if the application verifies tokens with an empty key. The vulnerability arises because the library does not reject zero-length keys, resulting in a deterministic HMAC digest that anyone can reproduce. This issue affects OAuth 2.0 resource servers and OIDC relying parties using Authlib for token verification.

References

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