CVE-2026-105280
What it is
Improper Validation of Integrity Check Value vulnerability in hexpm hex allows a package mirror to substitute the tarball that mix hex.package fetch PACKAGE VERSION --output - writes to standard output. Hex compares a fetched tarball's inner and outer checksums with the repository's signed registry before writing it to a file or unpacking it. The standard output branch of mix hex.package fetch writes the bytes returned by Hex.SCM.fetch/3 without that comparison, and Hex.SCM.fetch/3 doesn't verify freshly downloaded tarballs itself. When a mirror configured with HEX_MIRROR_URL or mirror_url serves altered bytes, the command prints them and exits successfully, while the same fetch with --output FILE fails with a checksum mismatch. Hex also prints diagnostics to standard output while the command runs: the body of a failed HTTP response from the update check or a registry fetch, and API warnings from the x-hex-message header. A mirror that answers one of those requests with an error whose body is a tar archive gets that archive written to standard output ahead of the verified tarball, so a pipeline that unpacks standard output extracts the mirror's files. This happens even when the checksum check then fails, because the archive is already on standard output. This issue affects hex: from 0.20.2 before 2.5.2.
At a glance
- Exploitability
- Can be exploited over the network without logging in, but needs a user to act. High risk of data tampering.
- Exploit odds
- 0.2% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.2% in the next 30 days (EPSS).
- Severity: 6.9 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.2% · EPSS, next 30 days
- Weakness
- CWE-354
- Record status
- Deferred
Attack profile CVSS 4.0 · 6.9
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- Present
- Privileges needed
- None
- User interaction
- Active
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Raw vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-105280.md and follow it. Check whether this project is affected by CVE-2026-105280. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/hexpm/hex/commit/69489f8b74213f03db10169e6e5407e6d5fee512
- https://github.com/hexpm/hex/commit/8a14632ca6ba8a8afd2a3f2098bc267c13e13d93
- https://github.com/hexpm/hex/commit/d1f5a085d9d4748e1f7d195e4bc39ebd77c28d9c
- https://github.com/hexpm/hex/security/advisories/GHSA-98jr-23pm-vj7c
References
- https://cna.erlef.org/cves/CVE-2026-105280.html
- https://github.com/hexpm/hex/commit/69489f8b74213f03db10169e6e5407e6d5fee512
- https://github.com/hexpm/hex/commit/8a14632ca6ba8a8afd2a3f2098bc267c13e13d93
- https://github.com/hexpm/hex/commit/d1f5a085d9d4748e1f7d195e4bc39ebd77c28d9c
- https://github.com/hexpm/hex/security/advisories/GHSA-98jr-23pm-vj7c
- https://osv.dev/vulnerability/EEF-CVE-2026-105280