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Fencer Vulns
medium 4.6

CVE-2026-66485 json

Uncontrolled Memory Allocation in GNU cpio

published 2026-08-10 2 mo ago modified 2026-10-24 16 d ago also EUVD-2026-55255

cvss
4.6
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

GNU cpio is vulnerable to an uncontrolled memory allocation in the make_path function at src/makepath.c. The function uses alloca to allocate stack memory based on the length of argpath, which is derived from an archive-controlled pathname during extraction. A malicious cpio archive containing a sufficiently long nested pathname causes an unbounded stack allocation, resulting in a stack overflow and crash of the cpio process. An attacker who can supply a crafted cpio archive to a victim who extracts it can cause a denial of service.

This issue has been fixed in commit 3cd514031371d8aeeaf2048aa10103e02831aaa9

Patch / fix

  • cpio Ubuntu 22.04 LTS 2.13+dfsg-7ubuntu0.2
  • cpio Ubuntu 24.04 LTS 2.15+dfsg-1ubuntu2.1
  • cpio Ubuntu 26.04 LTS 2.15+dfsg-2.1ubuntu0.1
  • cpio Ubuntu Pro 14.04 LTS 2.11+dfsg-1ubuntu1.2+esm3
  • cpio Ubuntu Pro 16.04 LTS 2.11+dfsg-5ubuntu1.1+esm2
  • cpio Ubuntu Pro 18.04 LTS 2.12+dfsg-6ubuntu0.18.04.4+esm1
  • cpio Ubuntu Pro 20.04 LTS 2.13+dfsg-2ubuntu0.4+esm1

ubuntu advisories UBUNTU-CVE-2026-66485

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • cpio hummingbird 1 2.15-10.3.hum1

red hat advisories RHSA-2026:82414

  • cpio SLE Module for Basesystem 15 SP7, SLE Micro 5.5, SLE Micro 5.4 +1 more 2.13-150400.3.10.1
  • cpio SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.15-160000.3.1
  • cpio Linux Micro 6.0 2.15-2.1
  • cpio Linux Micro 6.1 2.15-slfo.1.1_3.1
  • cpio SLES LTSS Extended Security 12 SP5 2.11-36.25.1

suse advisories SUSE-SU-2026:4012-1SUSE-SU-2026:23464-1SUSE-SU-2026:23612-1SUSE-SU-2026:3959-1SUSE-SU-2026:23441-1SUSE-SU-2026:23355-1

  • cpio openSUSE Leap 16.0 2.15-160000.3.1
  • cpio openSUSE Tumbleweed 2.15-8.1

opensuse advisories openSUSE-SU-2026:21747-1openSUSE-SU-2026:11618-1

  • cpio Azure Linux 3.0 2.14-2

azure linux advisories AZL-94692

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-66485 updated cvss 5.0

cpio: GNU cpio: Denial of Service via uncontrolled memory allocation from crafted archives

  • Red Hat Enterprise Linux 6 cpio 2.15-3.el10 Red Hat Enterprise Linux 7 cpio, cpio 2.15-3.el10 Red Hat Enterprise Linux 8 cpio, cpio 2.15-3.el10 Red Hat Enterprise Linux 9 cpio 2.15-3.el10 Red Hat Enterprise Linux 10 cpio 2.15-3.el10
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images cpio 2.15-10.3.hum1
    fixed: vendor fix RHSA-2026:82414

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 4.6 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 4.6 CVSS:4.0/AV:L/AC:L/AT:N/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

Affected products

  • GNU cpio

Classification

Weakness
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.