CVE WatchJul 24, 2026

CVE-2026-34240

JOSE is a Javascript Object Signing and Encryption (JOSE) library. Prior to version 0.3.5+1, a vulnerability in jose could allow an unauthen

CVSS

7.5

High

EPSS

0.1%

KEV

—

Exploit Today

0-100

Published: Mar 31, 2026 · Last modified: Jul 24, 2026 · CWE-347

EPSS · 30d

0.1%EPSS · 30 days0.2%

2026-09-282026-10-25

Technical description

JOSE is a Javascript Object Signing and Encryption (JOSE) library. Prior to version 0.3.5+1, a vulnerability in jose could allow an unauthenticated, remote attacker to forge valid JWS/JWT tokens by using a key embedded in the JOSE header (jwk). The vulnerability exists because key selection could treat header-provided jwk as a verification candidate even when that key was not present in the trusted key store. Since JOSE headers are untrusted input, an attacker could exploit this by creating a token payload, embedding an attacker-controlled public key in the header, and signing with the matching private key. Applications using affected versions for token verification are impacted. This issue has been patched in version 0.3.5+1. A workaround for this issue involves rejecting tokens where header jwk is present unless that jwk matches a key already present in the application's trusted key store.

Official references

Related CVEs

CVECVSSEPSSKEVRExploitTitleMod.

CVE-2026-65632—

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———The jose library accepts ECDSA (ES256, ES256K, ES384, and ES512) JWS signatures of a non-canonical length. When verifying an ECDSA signature, jose_jwk_kty_ec:verify/4 in src/jwk/jose_jwk_kty_ec.erl splits the raw signature in half by its actual byte length (split_binary(Signature, byte_size(Signature) div 2)) instead of enforcing the fixed length required by RFC 7518 §3.4, and then decodes each half with crypto:bytes_to_integer/1, which ignores leading zero bytes. As a result, an attacker who holds one valid token can prepend leading zero bytes to each of the R and S halves to produce longer signatures that still split evenly and decode to the same (r, s) pair, so many distinct signature byte strings all verify against the same key (signature malleability). This does not allow forging new payloads or impersonating a signer, because the underlying (r, s) values are unchanged. It does defeat any security control that assumes a valid token or its signature is unique, such as token-revocation-by-hash, replay or idempotency caches, and deduplication logic. This issue affects jose: from 1.0.0 before 1.11.13.6h CVE-2026-1161168.2 HIG

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——0A vulnerability was detected in Yoosee GM8135S Camera 21.00.01.36. Affected is an unknown function of the component Secure Boot. Performing a manipulation results in improper verification of cryptographic signature. The attack needs to be approached locally. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.13h CVE-2026-1161897.5 HIG

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——0rclone from 1.55.0 before 1.75.2 contains a signature verification bypass in stable selfupdate that trusts checksums from unsigned bytes preceding the PGP-clearsigned SHA256SUMS block. Attackers controlling the release distribution path can prepend an unsigned checksum line matching a malicious archive, causing selfupdate to install an attacker-controlled rclone executable.12h CVE-2026-568378.6 HIG

8.3%

——2PraisonAI is a multi-agent teams system. From version 4.6.56 to before version 4.6.59, PraisonAI's LinearBot starts a public webhook listener on 0.0.0.0 and treats LINEAR_WEBHOOK_SECRET as optional. When the secret is absent, startup only logs a warning and _handle_webhook() skips Linear-Signature verification entirely. An unauthenticated network caller who can reach the webhook endpoint can submit a forged Linear-Event: AgentSession request. The forged request is parsed, scheduled for background processing, dispatched to _handle_agent_session(), and passed into BotSessionManager.chat(). The bot then attempts to post the agent response back to Linear under the configured bot token. The PoV is offline and deterministic. It does not contact Linear. It calls the webhook handler directly, monkey-patches the outbound Linear comment path, and proves both sides of the boundary. This issue has been patched in version 4.6.59.3d CVE-2026-89317—

3.9%

——1gose parsed the JWS `crit` header into `JwsHeader.Crit` and then never read it. RFC 7515 §4.1.11 requires a recipient to reject a JWS whose listed critical extension parameters it does not understand. gose implements no header extensions, so every token carrying a non-empty `crit` should have been rejected — and none were.3d CVE-2026-1146157.4 HIG

2.4%

——1Authlib is a Python library which builds OAuth and OpenID Connect servers. From 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlib's PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0.3d