What is CVE-2026-105280?

CVE-2026-105280 is Hex writes unverified package tarballs to standard output in mix hex.package fetch. The supplied enrichment data classifies it as Unclassified mapped to CWE-354 CWE-354.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-105280. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-105280 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

1 public PoC repositories reported; 0 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-105280 using CVSS 6.9, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

Workarounds are not confirmed from current sources. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

mediumpublic exploit

CVE-2026-105280

CVE-2026-105280 — Hex writes unverified package tarballs to standard output in mix hex.package fetch

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.

Published Oct 12, 2026Updated Oct 12, 2026Sources: NVD, hexpm (CNA), GitHub, Red Hat (VEX), SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Exploit code

public exploit, none observed

EPSS

ahead of 0% of scored CVEs

Affects

hexpm

2 products listed

CVSS base

6.9

medium · 2 sources

Remediation

The vendor's own words where we have them.

Upgrade Hex to 2.5.2 or later, for example with mix local.hex. mix hex.package fetch PACKAGE VERSION --output - then verifies the registry checksum before writing the tarball to standard output and prints its messages to standard error.

Red Hat VEX · CVE-2026-105280

fixed0affected0not affected1

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
hexpm	hex	0.20.2 to < 2.5.2	Vulnerable
hexpm	hex	d1f5a085d9d4748e1f7d195e4bc39ebd77c28d9c	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Scope

Attack Complexity

Low

Attack Vector

Network

Privileges Req

None

User Interaction

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
6.9	CVSS 4.0	medium	—	—	hexpm (CNA)
5.3	CVSS 3.1	medium	—	—	Red Hat (VEX)

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

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-354 · Improper Validation of Integrity Check Value

Modify Application Data
Other
Hide Activities

Mitigation: Ensure that the checksums present in messages are properly checked in accordance with the protocol specification before they are parsed and used.::

Weakness & attack patterns

CWE-354

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-463 · Padding Oracle Crypto AttackCAPEC-145 · Checksum SpoofingCAPEC-75 · Manipulating Writeable Configuration Files

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Search application, proxy, and WAF logs for requests touching /3.
Prioritize edge telemetry for network-reachable hex.
Monitor for scanner or exploit-pattern traffic after 1 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 6.9 (AV:N)
Oct 12, 2026 · NVD
Initial · CVE published
Oct 12, 2026 · NVD
CVE published by MITRE.
Oct 12, 2026 · SOCRadar CTI

References

8 on the record

cna.erlef.org/cves/CVE-2026-105280.html
Vendor Advisory, Mitre, NIST
github.com/hexpm/hex/commit/69489f8b74213f03db10169e6e5407e6d5fee512
Exploit, Third Party Advisory, Mitre, NIST
github.com/hexpm/hex/commit/8a14632ca6ba8a8afd2a3f2098bc267c13e13d93
Exploit, Third Party Advisory, Mitre, NIST
github.com/hexpm/hex/commit/d1f5a085d9d4748e1f7d195e4bc39ebd77c28d9c
Exploit, Third Party Advisory, Mitre, NIST
github.com/hexpm/hex/security/advisories/GHSA-98jr-23pm-vj7c
Exploit, Third Party Advisory, Mitre, NIST
osv.dev/vulnerability/EEF-CVE-2026-105280
Vendor Advisory, Mitre, NIST
access.redhat.com/security/cve/CVE-2026-105280
Vendor Advisory
www.cve.org/CVERecord?id=CVE-2026-105280
Vendor Advisory

Elsewhere on this site

hexpmevery CVE for this vendor
Unclassifiedsame class
CWE-354other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-105280 is Hex writes unverified package tarballs to standard output in mix hex.package fetch, a medium vulnerability affecting hex from hexpm. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-105280. Public exploit evidence is: 1 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 6.9 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.