{"id":"CVE-2026-65625","revision":"8a7f79f887a844dcbc98ac2e5c570904","records":[{"revision":"8a7f79f887a844dcbc98ac2e5c570904","observedAt":"2026-10-26T20:35:31.018+00:00","statement":{"source":"cve-program","id":"CVE-2026-65625","aliases":[],"title":"Attacker-controlled AES-GCM authentication tag length allows tag forgery in jose","description":"The pure-Erlang AES-GCM fallback in jose_jwa_aes derives the number of verified authentication tag bits from the attacker-supplied tag itself. In the {aes_gcm, Bits} clause of block_decrypt/4, the incoming tag is guarded only by is_binary/1, with no check on its length. Verification in gcm_block_decrypt/6 then computes TBits = bit_size(T) and compares only those bits of the real 128-bit tag. An attacker who controls a JWE token can truncate the authentication tag to as little as 8 bits, so only 8 bits are ever checked. This reduces forgery resistance from 2^-128 to 2^-8, and a forged ciphertext is reliably accepted as authentic within 256 attempts without knowledge of the key (an authentication tag forgery and integrity bypass). Supplying a tag longer than 128 bits instead causes a badmatch that crashes the decrypting process. The fallback is reached through the public JWE decryption path whenever AES-GCM is not provided by a native crypto NIF, for example on FIPS or stripped or older OTP builds.\n\nThis issue affects jose: from 1.2.0 before 1.11.13.","state":0,"publishedAt":"2026-10-26T19:52:54.987+00:00","modifiedAt":"2026-10-26T19:52:54.987+00:00","affected":[{"ecosystem":"https://repo.hex.pm","name":"jose","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://repo.hex.pm\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"jose_jwa_aes\"\n                    ],\n                    \"packageName\": \"jose\",\n                    \"packageURL\": \"pkg:hex/jose\",\n                    \"product\": \"jose\",\n                    \"programFiles\": [\n                        \"src/jwa/jose_jwa_aes.erl\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"jose_jwa_aes:block_decrypt/4\"\n                        },\n                        {\n                            \"name\": \"jose_jwa_aes:gcm_block_decrypt/6\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/potatosalad/erlang-jose\",\n                    \"vendor\": \"potatosalad\",\n                    \"versions\": [\n                        {\n                            \"lessThan\": \"1.11.13\",\n                            \"status\": \"affected\",\n                            \"version\": \"1.2.0\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"https://github.com","name":"potatosalad/erlang-jose","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"collectionURL\": \"https://github.com\",\n                    \"cpes\": [\n                        \"cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*\"\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"modules\": [\n                        \"jose_jwa_aes\"\n                    ],\n                    \"packageName\": \"potatosalad/erlang-jose\",\n                    \"packageURL\": \"pkg:github/potatosalad/erlang-jose\",\n                    \"product\": \"jose\",\n                    \"programFiles\": [\n                        \"src/jwa/jose_jwa_aes.erl\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"jose_jwa_aes:block_decrypt/4\"\n                        },\n                        {\n                            \"name\": \"jose_jwa_aes:gcm_block_decrypt/6\"\n                        }\n                    ],\n                    \"repo\": \"https://github.com/potatosalad/erlang-jose\",\n                    \"vendor\": \"potatosalad\",\n                    \"versions\": [\n                        {\n                            \"lessThan\": \"3fa1f8e3efda0da5ce6f4c9984789f979dc02740\",\n                            \"status\": \"affected\",\n                            \"version\": \"8848b172575fb7d7e1e2977e8ae0a21678d2157a\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N","score":5.9,"severity":"MEDIUM"}],"references":["https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-6gxw-6f7r-cjr6","https://cna.erlef.org/cves/CVE-2026-65625.html","https://osv.dev/vulnerability/EEF-CVE-2026-65625","https://github.com/potatosalad/erlang-jose/commit/8848b172575fb7d7e1e2977e8ae0a21678d2157a","https://github.com/potatosalad/erlang-jose/commit/3fa1f8e3efda0da5ce6f4c9984789f979dc02740"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-65625","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-65625","identifiers":["CVE-2026-65625"]},"retained":false,"historicalAffected":[]}],"coverage":[]}