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VulnerabilityPublished

CVE-2026-114615: Kaskade · Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys

Affects kaskadeSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-114615· High 7.4

Not known to be exploited · CVSS 7.4 High.

Data as of 30 Oct 2026, 08:44 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
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
Homebrewkaskadepkg:brew/kaskadeOther threatsAffected
  • >=4.0.4
Fixed in–

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

AI-suggested

Since the vulnerability stems from an incomplete guard in OctKey.import_key(), users should avoid passing PEM or certificate keys with leading bytes to the jwt.decode function or restrict usage to asymmetric or symmetric algorithms exclusively, not both simultaneously. Review vendor advisories for updates and apply any forthcoming official fixes. Until then, avoid configurations that allow mixed algorithm lists or keys with leading whitespace or BOM characters.

Description

A vulnerability in Authlib's Kaskade implementation allows an attacker to forge HMAC-signed JWT tokens by exploiting an incomplete fix for algorithm confusion. The issue arises because the check preventing asymmetric public keys from being used as HMAC secrets only matches keys starting exactly at byte 0, while the loader accepts keys with leading bytes such as newlines or spaces. This permits an attacker with only the issuer's public key to create valid HS256 tokens with arbitrary claims that are accepted as authentic.

References

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