Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in potatosalad jose…

Why it is Yellow

• CVSS 6.9 medium

References

• https://cna.erlef.org/cves/CVE-2026-65627.html
• https://github.com/potatosalad/erlang-jose/commit/857eb8e7f2d33e2c9ca2189e77226561cacaf2ad
• https://github.com/potatosalad/erlang-jose/commit/a7746ecd4950f85a393136e449a91dac62b5c429
• https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gm
• https://osv.dev/vulnerability/EEF-CVE-2026-65627

Original description

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in potatosalad jose (erlang-jose) allows a remote attacker to exhaust a node's memory with a small crafted JWE token. The jose_jwe_zip:uncompress/2 function in src/jwe/jose_jwe_zip.erl decompresses the DEFLATE-compressed plaintext of a JWE that carries the optional zip: DEF header by calling zlib:inflate/2 on the entire attacker-controlled stream, with no bound on the output size or the inflation ratio. Raw DEFLATE reaches ratios around 1000:1 on highly repetitive input, so a few-kilobyte token inflates to hundreds of megabytes or gigabytes in a single call. Decompression runs automatically during decryption through jose_jwe:block_decrypt/2 (JOSE.JWE.block_decrypt/2 in Elixir), before the recipient can inspect or reject the payload. With the common asymmetric key-management algorithms (RSA-OAEP, ECDH-ES) an attacker needs only the recipient's public key to craft such a token, so no authentication or secret material is required. A single small token can exhaust the node's memory and crash the BEAM, denying service to all users. This issue affects jose: from 1.0.0 before 1.11.13.