CVE-2026-96618: Hex exhausts memory and disk on oversized or compressed responses from an untrusted mirror
hexpm · hex
Fixed in 2.5.2 · Affected: hexpm before 2.5.2 · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 29% of scored CVEs
DescriptionCVE.org
Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in hexpm hex allows an untrusted package mirror to exhaust the memory or disk space of the machine running mix deps.get, mix deps.update, mix hex.package fetch or mix hex.docs fetch. Hex treats a mirror configured with HEX_MIRROR_URL, HEX_MIRROR or mirror_url as untrusted: it doesn't send credentials to it, and it checks registry signatures and package checksums that the mirror can't forge. Several response paths consume memory or disk in proportion to what the mirror sends before any of those checks run. Hex.HTTP.request/5 reads the whole response body into memory and decompresses it with :zlib.gunzip/1 whenever the response's Content-Encoding contains gzip, with no limit on the compressed or decompressed size. Hex doesn't ask for compressed responses, so the server decides whether this step runs. It applies to registry, package, docs and API responses. Package tarballs have no download size limit. Hex 2.5.1 holds the whole tarball in memory and writes it to the cache, and the development branch streams it to a temporary file; the 16 MiB tarball limit is checked only when the file is unpacked. The tarball is then unpacked, into deps/<app> in 2.5.1 and into a staging directory on the development branch, before its checksums are compared with the registry. mix hex.docs fetch, and mix hex.docs offline when docs are missing, write the docs tarball to disk and extract it with :mix_hex_erl_tar.extract/2 without the 16 MiB compressed and 128 MiB decompressed limits that mix_hex_tarball:unpack_docs/3 applies. The signed registry doesn't cover docs tarballs, so nothing checks them. Registry responses are also decompressed before their signature is checked, in hex_core code that Hex vendors; that part is tracked in https://github.com/hexpm/hex_core/security/advisories/GHSA-7c4r-cgf9-9jmq. This issue affects hex: from 0.11.2 before 2.5.2.
Affected products2
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- hexpm · hexfrom 0.11.2 before 2.5.2
- hexpm · hexVersions not stated
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- hexpm
- Published
- October 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-96618 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.