Skip to main content
VulnerabilityPublished Updated

CVE-2026-65626: jose · pure-Erlang RSAES-PKCS1-v1_5 decryption

Affects joseSource GCVE Database

0
Authoritative record:CVE-2026-65626· Medium 5.9

Not known to be exploited · CVSS 5.9 Medium.

Data as of 28 Oct 2026, 22:28 UTC

CVSS 4.0 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10josepkg:deb/ubuntu/jose?arch=source&distro=stonkingOther threatsAffected
  • =14-2build1
  • =14-2build2
Fixed in–
Ubuntu 26.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=resoluteOther threatsAffected
  • =14-2build1
Fixed in–
Ubuntu 24.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=nobleOther threatsAffected
  • 11-2 – 13-1
5 affected builds
Fixed in–
Ubuntu 22.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=jammyOther threatsAffected
  • =10-3
  • =11-2
Fixed in–
Ubuntu 20.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=focalOther threatsAffected
  • =10-2build2
Fixed in–
Ubuntu 18.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=bionicOther threatsAffected
  • =10-2
  • =10-2build1
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

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.

References

Community reviews

Loading reviews…