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/ 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.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
Upgrade Hex to 2.5.2 or later, for example with mix local.hex (from the CVE record's solution, Erlang Ecosystem Foundation). Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact partial (CVSS v4.0 confidentiality and integrity impact neither High). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact partial (CVSS v4.0 confidentiality and integrity impact neither High). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it