CVE-2026-65627
Decompression bomb via unbounded zlib:inflate in jose_jwe_zip:uncompress/2
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.
Fixes and workarounds
Workaround
Reject JWE tokens that carry a zip header before passing them to jose_jwe:block_decrypt/2. DEFLATE compression is rarely used in legitimate JWE traffic, so untrusted tokens whose protected header contains zip: DEF can be inspected and filtered out before decryption.
Source: CNA: EEFFix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: EEFAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| jose potatosalad jose
hex |
≥ 1.0.0; < 1.11.13 (affected, semver)
Other versions: unaffected |
CNA: EEF |
| jose potatosalad potatosalad/erlang-jose
github |
≥ a7746ecd4950f85a393136e449a91dac62b5c429; < 857eb8e7f2d33e2c9ca2189e77226561cacaf2ad (affected, git)
Other versions: unaffected |
CNA: EEF |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.9 medium |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CNA: EEF |
Exploit evidence
- https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gm
exploit · ADP: CISA-ADP
References
- https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gmCNA: EEF · vendor-advisory, related
- https://cna.erlef.org/cves/CVE-2026-65627.htmlCNA: EEF · related
- https://osv.dev/vulnerability/EEF-CVE-2026-65627CNA: EEF · related
- https://github.com/potatosalad/erlang-jose/commit/a7746ecd4950f85a393136e449a91dac62b5c429CNA: EEF · related
- https://github.com/potatosalad/erlang-jose/commit/857eb8e7f2d33e2c9ca2189e77226561cacaf2adCNA: EEF · patch
- https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gmADP: CISA-ADP · exploit
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