CVE-2026-65626: jose · pure-Erlang RSAES-PKCS1-v1_5 decryption
Affects joseSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium.
Data as of 28 Oct 2026, 22:28 UTC
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 26 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10josepkg:deb/ubuntu/jose?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 20.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Ubuntu 18.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=bionicOther threats | Affected
| 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
- ubuntu.com/security/CVE-2026-65626 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-65626 (opens in a new tab)
- cna.erlef.org/cves/cve-2026-65626.html (opens in a new tab)
- github.com (opens in a new tab)
- github.com/potatosalad/erlang-jose (opens in a new tab)
- github.com/potatosalad/erlang-jose/commit/0eac8cef9aaa48fb6846f4e47a0002dc4a73966d (opens in a new tab)
- github.com/potatosalad/erlang-jose/commit/853c5d4c4c0bd2a7ecb055b237f4284184e176c8 (opens in a new tab)
- github.com/potatosalad/erlang-jose/security/advisories/ghsa-vwvr-f994-6j9j (opens in a new tab)
- hex.pm/packages/jose (opens in a new tab)
- repo.hex.pm (opens in a new tab)
- github.com/cveproject/cvelistv5/tree/main/cves/2026/65xxx/cve-2026-65626.json (opens in a new tab)
- nvd.nist.gov/vuln/detail/cve-2026-65626 (opens in a new tab)
- osv.dev/vulnerability/eef-cve-2026-65626 (opens in a new tab)