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Fencer Vulns
high 7.5

CVE-2026-48959 json

IO::Uncompress::Unzip versions before 2.220 for Perl allow CPU exhaustion via per-byte read loop in fastForward

published 2026-05-27 5 mo ago modified 2026-07-24 3 mo ago also EUVD-2026-32043

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

IO::Uncompress::Unzip versions before 2.220 for Perl allow CPU exhaustion via per-byte read loop in fastForward.

fastForward() compares length $offset (the digit count of the offset, 1 to 19) against the chunk size $c instead of $offset itself, so $c shrinks from 16 KiB to 1-19 bytes per iteration.

Extracting a named entry from an attacker supplied zip via IO::Uncompress::Unzip->new($zip, Name => $target) drives a per-byte read loop scaling with the entry's compressed size, up to the non-Zip64 4 GiB cap.

Patch / fix

  • PMQS IO::Uncompress::Unzip 2.220
  • perl Debian 12 5.36.0-7+deb12u4
  • perl Debian 13 5.40.1-6+deb13u1
  • perl Debian 14 5.40.1-8
  • libio-compress-perl Debian 12 2.204-1+deb12u1
  • libio-compress-perl Debian 13 2.213-1+deb13u1
  • libio-compress-perl Debian 14 2.220-1

debian advisories DEBIAN-CVE-2026-48959

  • perl Ubuntu 24.04 LTS 5.38.2-3.2ubuntu0.4

ubuntu advisories UBUNTU-CVE-2026-48959

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

  • perl Alpine 3.24 5.42.3-r0

alpine advisories ALPINE-CVE-2026-48959

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • perl Azure Linux 3.0 5.38.2-512

azure linux advisories AZL-89307

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-2026-48959 updated cvss 5.0

perl-IO-Compress: perl-IO-Compress: CPU exhaustion via per-byte read loop in fastForward

  • Red Hat Enterprise Linux 7 perl-IO-Compress
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perl-IO-Compress Red Hat Enterprise Linux 9 perl-IO-Compress Red Hat Enterprise Linux 10 perl-IO-Compress
    affected: workaround, no fix available “Fix deferred”

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
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • PMQS IO::Uncompress::Unzip

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

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.