PT-2026-29287 · Jose · Jose

Rbellens · Published 2026-03-31 · Updated 2026-03-31 · CVE-2026-34240

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Name of the Vulnerable Software and Affected Versions jose versions prior to 0.3.5+1

Description A flaw in jose could allow a remote attacker to forge valid JWS/JWT tokens by utilizing a key embedded in the JOSE header (jwk). The issue arises because key selection may consider header-provided jwk as a verification candidate even if the key is not in the trusted key store. An attacker can exploit this by crafting a token payload, embedding an attacker-controlled public key in the header, and signing with the corresponding private key. Applications using affected versions for token verification are susceptible to this issue.

Recommendations Upgrade to version 0.3.5+1 or later. Reject tokens where a header jwk is present unless that jwk matches a key already present in the application's trusted key store.

Exploit

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

CVE-2026-34240

GHSA-VM9R-H74P-HG97

Affected Products

Jose

References · 7

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34240.json · Exploit
• https://osv.dev/vulnerability/CVE-2026-34240 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-vm9r-h74p-hg97 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-34240 · Security Note
• https://github.com/appsup-dart/jose · Note
• https://github.com/appsup-dart/jose/commit/b07799aac1f56a9a21483feac026272aab30cc5d · Note
• https://github.com/appsup-dart/jose/security/advisories/GHSA-vm9r-h74p-hg97 · Note