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CVE-2026-118669VulnerabilityPublished

s3ql · OAuthLib: Token grants can use attacker-supplied client_id for authorization after authenticating a different client

Affects s3qlSource GCVE Database

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Authoritative record:CVE-2026-118669· High 8.4

Not known to be exploited · CVSS 8.4 High : upgrade to 6.3.1_1 or 3.8.1 soon.

Data as of 31 Oct 2026, 16:36 UTC

CVSS 4.0 base score
8.4High
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 4.08.4
Patch
Available – fixed in 6.3.1_1, 3.8.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 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 30 Oct 2026.

What to do

Upgrade s3ql to 6.3.1_1 or 3.8.1.

Affected software

ProductAffectedFixed in
Homebrews3qlpkg:brew/s3qlOther threatsAffected
  • >=3.1 <3.8.1
  • >=6.0.0 <6.3.1_1
Fixed in
  • 3.8.1
  • 6.3.1_1

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 OAuthlib versions 3.8.1 and 6.3.1_1. Users should upgrade to these versions or later to remediate the vulnerability. Deployments should also review their RequestValidator implementations to ensure authorization decisions are based on the authenticated client object rather than the client_id argument passed by OAuthlib. No additional mitigation is required if the validator ignores the client_id argument and authorizes solely from request.client.

Description

OAuthlib versions prior to 3.8.1 and 6.3.1_1 contain a vulnerability in token grant handlers where an authenticated low-privilege client can supply a different client_id in the token request body. This causes grant and scope validation to be performed under the attacker-supplied client_id rather than the authenticated client's identity. The issue affects the client_credentials and password grant flows and can lead to unauthorized token issuance with elevated scopes or grants.

References

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