Signature forgery via incomplete RSA verification
Published Sep 10, 2026 · Updated Sep 10, 2026
Improper RSA signature verification in OCaml jose before 0.11.0 allows remote attackers to forge accepted signed messages. In jose/Jws.ml, verify_jwk accepted an RSA signature whenever PKCS1.sig_decode succeeded, without verifying the signed input with the public key. Exposure requires a consuming application to pass attacker-controlled JWS data to this path; accepted forgeries defeat authenticity and dependent authorization decisions.
Summary
What happened
Improper RSA signature verification in OCaml jose before 0.11.0 allows remote attackers to forge accepted signed messages. In jose/Jws.ml, verify_jwk accepted an RSA signature whenever PKCS1.sig_decode succeeded, without verifying the signed input with the public key. Exposure requires a consuming application to pass attacker-controlled JWS data to this path; accepted forgeries defeat authenticity and dependent authorization decisions.
The record
- CVE
- CVE-2026-89086
- Published
- Sep 10, 2026
- Updated
- Sep 10, 2026
- Vendor
- OCaml
- Product
- jose
- Classifications
- CWE-347
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 10, 2026CVE publishedPublication date reported by the CVE source.
- Sep 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.11.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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