{"id":"EEF-CVE-2026-65626","aliases":["CVE-2026-65626","GHSA-vwvr-f994-6j9j"],"title":"Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose","titleSource":"OSV","descriptionSource":"OSV","description":"## Summary\n\nThe 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.\n\nAn 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.\n\nThis issue affects jose: from 1.3.0 before 1.11.13.\n\n## Configurations\n\nThe vulnerable code path is only reached when jose performs RSAES-PKCS1-v1_5 decryption with its pure-Erlang fallback (the `jose_jwa_pkcs1` module) instead of the native OTP `public_key` implementation. This requires the crypto_fallback option to be enabled (`application:set_env(jose, crypto_fallback, true)`, or `JOSE.crypto_fallback(true)` in Elixir) and the OTP runtime not to provide native RSA1_5 decryption. When native OTP RSA support is selected, decryption does not go through `jose_jwa_pkcs1`.","severity":"medium","score":5.9,"published":"2026-10-26T19:53:05.620Z","modified":"2026-10-26T20:11:07.651Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Hex","name":"jose","sources":[{"name":"OSV · EEF-CVE-2026-65626","url":"https://osv.dev/vulnerability/EEF-CVE-2026-65626"}],"ranges":[{"events":[{"introduced":"1.3.0"},{"fixed":"1.11.13"}],"type":"SEMVER"}],"versions":["1.10.0","1.10.1","1.11.0","1.11.1","1.11.10","1.11.11","1.11.12","1.11.2","1.11.4","1.11.5","1.11.6","1.11.7","1.11.8","1.11.9","1.3.0","1.4.0","1.4.1","1.4.2","1.5.0","1.5.1","1.5.2","1.6.0","1.6.1","1.7.0","1.7.1","1.7.2","1.7.3","1.7.4","1.7.5","1.7.6","1.7.7","1.7.8","1.7.9","1.8.0","1.8.1","1.8.2","1.8.3","1.8.4","1.9.0"],"fixed":["1.11.13"]}],"sourceAffected":[{"ranges":[{"events":[{"introduced":"853c5d4c4c0bd2a7ecb055b237f4284184e176c8"},{"fixed":"0eac8cef9aaa48fb6846f4e47a0002dc4a73966d"}],"type":"GIT","repo":"https://github.com/potatosalad/erlang-jose"}],"versions":["1.11.12","1.11.11","1.11.10","1.11.9","1.11.8","1.11.7","1.11.5","1.11.4","1.11.2","1.11.1","1.11.0","1.10.1","1.10.0","1.9.0","1.8.4","1.8.3","1.8.2","1.8.1","1.8.0","1.7.9","1.7.8","1.7.7","1.7.6","1.7.5","1.7.4","1.7.3","1.7.2","1.7.1","1.7.0","1.6.1","1.6.0","1.5.2","1.5.1","1.5.0","1.4.2","1.4.1","1.4.0","1.3.0"]}],"references":["https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-vwvr-f994-6j9j","https://cna.erlef.org/cves/CVE-2026-65626.html","https://github.com/potatosalad/erlang-jose/commit/853c5d4c4c0bd2a7ecb055b237f4284184e176c8","https://github.com/potatosalad/erlang-jose/commit/0eac8cef9aaa48fb6846f4e47a0002dc4a73966d","https://hex.pm/packages/jose","https://osv.dev/vulnerability/EEF-CVE-2026-65626"],"sources":[{"name":"OSV","id":"EEF-CVE-2026-65626","modified":"2026-10-26T20:11:07.651789963Z","url":"https://osv.dev/vulnerability/EEF-CVE-2026-65626"},{"name":"CVE","id":"CVE-2026-65626","modified":"2026-10-26T19:53:05.620Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-65626"}],"assessments":[{"source":"OSV","vector":"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","score":5.9},{"source":"EEF","vector":"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","score":5.9}],"products":[{"vendor":"potatosalad","name":"jose","platforms":[],"versions":[{"version":"1.3.0","status":"affected","lessThan":"1.11.13","versionType":"semver"}],"defaultStatus":"unaffected","source":"EEF","url":"https://www.cve.org/CVERecord?id=CVE-2026-65626"},{"vendor":"potatosalad","name":"jose","platforms":[],"versions":[{"version":"853c5d4c4c0bd2a7ecb055b237f4284184e176c8","status":"affected","lessThan":"0eac8cef9aaa48fb6846f4e47a0002dc4a73966d","versionType":"git"}],"defaultStatus":"unaffected","source":"EEF","url":"https://www.cve.org/CVERecord?id=CVE-2026-65626"}],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T21:40:30.742Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}