{"id":"DEBIAN-CVE-2026-65626","details":"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.","modified":"2026-10-27T17:00:07.776090187Z","published":"2026-10-26T20:17:58.103Z","upstream":["CVE-2026-65626"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-65626"}],"affected":[{"package":{"name":"erlang-jose","ecosystem":"Debian:12","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.10-1~bpo12+1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1","1.11.5-1","1.11.6-1","1.11.6-1~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65626.json"}},{"package":{"name":"erlang-jose","ecosystem":"Debian:13","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65626.json"}},{"package":{"name":"erlang-jose","ecosystem":"Debian:14","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65626.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}