medium · CVSS 6.9

CVE-2026-65627

Decompression bomb via unbounded zlib:inflate in jose_jwe_zip:uncompress/2

Published 26 Oct 2026 · Source updated 2 Nov 2026 · Retrieved 2026-11-04 09:34 UTC · This record may be stale; verify the source

Statance checks for CVE-2026-65627. Connected servers are checked automatically against the fixed versions their distribution or package ecosystem has published for it, including app dependency lockfiles. Check my servers ↗

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What happened?

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.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
Software	Version information	Fixed version
josepotatosalad	affected: 1.0.0 to < 1.11.13	See vendor advisory
potatosalad/erlang-josepotatosalad	affected: a7746ecd4950f85a393136e449a91dac62b5c429 to < 857eb8e7f2d33e2c9ca2189e77226561cacaf2ad	See vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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