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CVE.org (no NVD analysis yet)· CNA EEF

CVE-2026-96618: Hex exhausts memory and disk on oversized or compressed responses from an untrusted mirror

LowCVSS 2.1 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 8/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.35% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • Fixed version: hexpm hex 08956100a8283ba500a123e5539ac64d5d7e91d8, 2.5.2, bb5189eade682c5fc3f98d9725973a7beb4e1deb.

Low priority for now. Upgrade to hexpm hex 08956100a8283ba500a123e5539ac64d5d7e91d8, 2.5.2, bb5189eade682c5fc3f98d9725973a7beb4e1deb or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Oct 12, 2026
Updated
Nov 11, 2026
EPSS
0.3% · 29th percentile

Report tools

JSON

Action score

8

Monitor

Low priority for now.

CVSS
8 / 40 · 2.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · EEF
2.1
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Follow CVE-2026-96618

When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (EEF). Independent of NVD's CPE analysis and usually ahead of it.

  • hexpm hex

    • 0.11.2 and later · before 2.5.2affected · semver
    • 51ea632424fb6ea8765148f96dc25dfeb526b1f8 and lateraffected · gitfixed in bb5189eade682c5fc3f98d9725973a7beb4e1deb, 08956100a8283ba500a123e5539ac64d5d7e91d8

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:13erlang-hexfrom 0—
Debian:14erlang-hexbefore 2.5.3-22.5.3-2

Same product

hexpm: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-96612Path traversal in Hex via unvalidated dependency app names
    30Monitor
  • CVE-2026-105668Hex release-age cooldown is lifted package-wide when the locked release is retired
    28Monitor
  • CVE-2026-105280Hex writes unverified package tarballs to standard output in mix hex.package fetch
    27Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-103503Oct 12, 2026 · Hex trusts its bundled CA certificates when cacerts_path is set
    23Monitor
  • ← EarlierCVE-2026-81856Oct 12, 2026 · Terminal escape sequence injection in Hex via unneutralized server-supplied output
    9Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
hexpm hex08956100a8283ba500a123e5539ac64d5d7e91d8Vendor (CNA)
hexpm hex2.5.2Vendor (CNA)
hexpm hexbb5189eade682c5fc3f98d9725973a7beb4e1debVendor (CNA)
debian:erlang-hex2.5.3-2 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 12, 2026+31 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Not on record for this CVE: variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
A
Scope
X

Weakness class (CWE)

CWE-409 · Improper Handling of Highly Compressed Data (Data Amplification)

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Exploit maturity— → none
  3. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records