{"id":"CVE-2026-65626","state":"PUBLISHED","title":"Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose","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.\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.","publishedAt":"2026-10-26T19:53:05.620Z","updatedAt":"2026-10-26T19:53:05.620Z","severity":{"score":5.9,"label":"Medium","version":"4.0","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","source":"EEF"},"assigner":"EEF","products":["potatosalad jose"],"affected":[{"vendor":"potatosalad","product":"jose","packageName":"jose","packageURL":"pkg:hex/jose","defaultStatus":"unaffected","versions":[{"version":"1.3.0","status":"affected","lessThan":"1.11.13","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*"],"modules":["jose_jwa_pkcs1"],"programFiles":["src/jwa/jose_jwa_pkcs1.erl"],"programRoutines":[{"name":"jose_jwa_pkcs1:decrypt_private/3"},{"name":"jose_jwa_pkcs1:rsaes_pkcs1_decrypt/2"},{"name":"jose_jwa_pkcs1:eme_pkcs1_decode/2"},{"name":"jose_jwa_pkcs1:dp/2"}],"repo":"https://github.com/potatosalad/erlang-jose"},{"vendor":"potatosalad","product":"jose","packageName":"potatosalad/erlang-jose","packageURL":"pkg:github/potatosalad/erlang-jose","defaultStatus":"unaffected","versions":[{"version":"853c5d4c4c0bd2a7ecb055b237f4284184e176c8","status":"affected","lessThan":"0eac8cef9aaa48fb6846f4e47a0002dc4a73966d","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*"],"modules":["jose_jwa_pkcs1"],"programFiles":["src/jwa/jose_jwa_pkcs1.erl"],"programRoutines":[{"name":"jose_jwa_pkcs1:decrypt_private/3"},{"name":"jose_jwa_pkcs1:rsaes_pkcs1_decrypt/2"},{"name":"jose_jwa_pkcs1:eme_pkcs1_decode/2"},{"name":"jose_jwa_pkcs1:dp/2"}],"repo":"https://github.com/potatosalad/erlang-jose"}],"references":["https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-vwvr-f994-6j9j","https://cna.erlef.org/cves/CVE-2026-65626.html","https://osv.dev/vulnerability/EEF-CVE-2026-65626","https://github.com/potatosalad/erlang-jose/commit/853c5d4c4c0bd2a7ecb055b237f4284184e176c8","https://github.com/potatosalad/erlang-jose/commit/0eac8cef9aaa48fb6846f4e47a0002dc4a73966d"],"weaknesses":["CWE-203"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/65xxx/CVE-2026-65626.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-65626","state":"PUBLISHED","datePublished":"2026-10-26T19:53:05.620Z","dateUpdated":"2026-10-26T19:53:05.620Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-07-22T13:55:59.401Z"},"containers":{"cna":{"title":"Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose","descriptions":[{"lang":"en","value":"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.\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."}],"affected":[{"vendor":"potatosalad","product":"jose","packageName":"jose","packageURL":"pkg:hex/jose","defaultStatus":"unaffected","versions":[{"version":"1.3.0","status":"affected","lessThan":"1.11.13","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*"],"modules":["jose_jwa_pkcs1"],"programFiles":["src/jwa/jose_jwa_pkcs1.erl"],"programRoutines":[{"name":"jose_jwa_pkcs1:decrypt_private/3"},{"name":"jose_jwa_pkcs1:rsaes_pkcs1_decrypt/2"},{"name":"jose_jwa_pkcs1:eme_pkcs1_decode/2"},{"name":"jose_jwa_pkcs1:dp/2"}],"repo":"https://github.com/potatosalad/erlang-jose"},{"vendor":"potatosalad","product":"jose","packageName":"potatosalad/erlang-jose","packageURL":"pkg:github/potatosalad/erlang-jose","defaultStatus":"unaffected","versions":[{"version":"853c5d4c4c0bd2a7ecb055b237f4284184e176c8","status":"affected","lessThan":"0eac8cef9aaa48fb6846f4e47a0002dc4a73966d","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*"],"modules":["jose_jwa_pkcs1"],"programFiles":["src/jwa/jose_jwa_pkcs1.erl"],"programRoutines":[{"name":"jose_jwa_pkcs1:decrypt_private/3"},{"name":"jose_jwa_pkcs1:rsaes_pkcs1_decrypt/2"},{"name":"jose_jwa_pkcs1:eme_pkcs1_decode/2"},{"name":"jose_jwa_pkcs1:dp/2"}],"repo":"https://github.com/potatosalad/erlang-jose"}],"references":[{"url":"https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-vwvr-f994-6j9j","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-65626.html","name":"EEF CNA record for CVE-2026-65626","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-65626","name":"OSV record EEF-CVE-2026-65626","tags":["related"]},{"url":"https://github.com/potatosalad/erlang-jose/commit/853c5d4c4c0bd2a7ecb055b237f4284184e176c8","name":"Introducing commit 853c5d4 in potatosalad/erlang-jose","tags":["related"]},{"url":"https://github.com/potatosalad/erlang-jose/commit/0eac8cef9aaa48fb6846f4e47a0002dc4a73966d","name":"Fix commit 0eac8ce in potatosalad/erlang-jose","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"LOCAL","baseScore":5.9,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-203","description":"CWE-203 Observable Discrepancy","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-10-26T19:53:05.620Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The vulnerable code path is only reached when jose performs RSAES-PKCS1-v1_5 decryption with its pure-Erlang fallback (the <code>jose_jwa_pkcs1</code> module) instead of the native OTP <code>public_key</code> implementation. This requires the crypto_fallback option to be enabled (<code>application:set_env(jose, crypto_fallback, true)</code>, or <code>JOSE.crypto_fallback(true)</code> 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 <code>jose_jwa_pkcs1</code>.</p>"},{"base64":false,"type":"text/markdown","value":"The 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`."}],"value":"The 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."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*","versionEndExcluding":"1.11.13","versionStartIncluding":"1.3.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"reporter","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Andrew Bennett"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-463","descriptions":[{"lang":"en","value":"CAPEC-463 Padding Oracle Crypto Attack"}]}],"source":{"discovery":"EXTERNAL"}}}}}