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CVE-2026-65626EUVD-2026-110304EEF-CVE-2026-65626GHSA-VWVR-F994-6J9J

Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.11.13
None on Exploit-DB, Metasploit or GitHub

Summary

The jose Erlang library (versions 1.3.0 up to but not including 1.11.13) is affected through its RSAES-PKCS1-v1_5 decryption code, which can act as a Bleichenbacher padding oracle. An unauthenticated attacker who can send ciphertexts to an endpoint that decrypts RSA1_5 JWE keys could potentially recover encrypted session keys and plaintext data, or forge signatures, by exploiting the padding-validity and timing differences in responses.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

The pure-Erlang RSAES-PKCS1-v1_5 decryption in the jose_jwa_pkcs1 module is a Bleichenbacher padding oracle. eme_pkcs1_decode/2 returns the recovered message when a decrypted block has valid PKCS#1 v1.5 padding (a leading 0x00 0x02, a padding string of at least eight non-zero bytes, and a 0x00 separator) and returns a distinct error result otherwise, and rsaes_pkcs1_decrypt/2 additionally returns {error, {badsize, _}} when the length check fails. The implementation applies no implicit-rejection countermeasure (RFC 8017 §7.2.2): it does not substitute a deterministic pseudo-random plaintext on a padding failure, so a one-bit padding-conformance signal leaks to the caller. Because the underlying modular exponentiation in dp/2 is a raw, non-blinded crypto:mod_pow/3, the padding check also stays distinguishable by timing even when an application normalizes every failure to a single error value. An unauthenticated attacker who knows only the public RSA key and can submit ciphertexts to a decryption endpoint that unwraps RSA1_5 JWE keys (or otherwise calls decrypt_private/3 with rsa_pkcs1_padding) can use this oracle to recover the plaintext of intercepted ciphertexts, such as content-encryption keys and thus the protected message, or to forge signatures, through roughly 10^4 to 10^6 adaptive chosen-ciphertext queries. This issue affects jose: from 1.3.0 before 1.11.13.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • jose

    From 1.3.0 · fixed in 1.11.13

  • potatosalad/erlang-jose

    From 853c5d4c4c0bd2a7ecb055b237f4284184e176c8 · fixed in 0eac8cef9aaa48fb6846f4e47a0002dc4a73966d

  • joseHex

    From 1.3.0 · fixed in 1.11.13

References 5

GitHub · potatosalad/erlang-jose

cna.erlef.org

osv.dev