# CVE-2026-48959: libperl5.38t64: IO::Uncompress::Unzip versions before 2.220 for Perl allow CPU exhaustion via per-byte read loop in fastForward

CVE-2026-48959 is fixed in 12 products on 1 platform, first by ALAS2023-2026-1825, released June 11, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-48959
- Priority: High
- CVSS: 7.5 (Medium)
- EPSS: 0.0055
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 26, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libio-compress-perl Debian 12.15 (bookworm) | 2.204-1+deb12u1 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | libio-compress-perl Debian 13.5 (trixie) | 2.213-1+deb13u1 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | libio-compress-perl Debian 14 | 2.220-1 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | libperl5.38t64 Ubuntu 24.04.5 LTS (noble) | 5.38.2-3.2ubuntu0.4 | [libperl5.38t64 5.38.2-3.2ubuntu0.4](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libperl5.38t64-5.38.2-3.2ubuntu0.4.md) | Jul 13, 2026 |
| Linux | perl Debian 12.15 (bookworm) | 5.36.0-7+deb12u4 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | perl Debian 13.5 (trixie) | 5.40.1-6+deb13u1 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | perl Debian 14 | 5.40.1-8 | [DEBIAN-CVE-2026-48959](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48959.md) | Jun 24, 2026 |
| Linux | perl Ubuntu 24.04.5 LTS (noble) | 5.38.2-3.2ubuntu0.4 | [perl 5.38.2-3.2ubuntu0.4](https://patchblox.com/security/data/fix/linux/ubuntu-noble-perl-5.38.2-3.2ubuntu0.4.md) | Jul 13, 2026 |
| Linux | perl-Compress-Raw-Bzip2 Fedora 43 | 2.218-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-Compress-Raw-Bzip2-debuginfo Fedora 43 | 2.218-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-Compress-Raw-Bzip2-debugsource Fedora 43 | 2.218-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-Compress-Raw-Bzip2-tests Fedora 43 | 2.218-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-IO-Compress Fedora 43 | 2.221-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-IO-Compress amzn 2023 | 2.217-1.amzn2023.0.2 | [ALAS2023-2026-1825](https://patchblox.com/security/data/fix/linux/alas2023-2026-1825.md) | Jun 11, 2026 |
| Linux | perl-IO-Compress-tests Fedora 43 | 2.221-1.fc43 | [FEDORA-2026-FB1F15CE04](https://patchblox.com/security/data/fix/linux/fedora-2026-fb1f15ce04.md) | Jun 22, 2026 |
| Linux | perl-IO-Compress-tests amzn 2023 | 2.217-1.amzn2023.0.2 | [ALAS2023-2026-1825](https://patchblox.com/security/data/fix/linux/alas2023-2026-1825.md) | Jun 11, 2026 |
| Linux | perl-base Ubuntu 24.04.5 LTS (noble) | 5.38.2-3.2ubuntu0.4 | [perl-base 5.38.2-3.2ubuntu0.4](https://patchblox.com/security/data/fix/linux/ubuntu-noble-perl-base-5.38.2-3.2ubuntu0.4.md) | Jul 13, 2026 |
| Linux | perl-debug Ubuntu 24.04.5 LTS (noble) | 5.38.2-3.2ubuntu0.4 | [perl-debug 5.38.2-3.2ubuntu0.4](https://patchblox.com/security/data/fix/linux/ubuntu-noble-perl-debug-5.38.2-3.2ubuntu0.4.md) | Jul 13, 2026 |
| Linux | perl-modules-5.38 Ubuntu 24.04.5 LTS (noble) | 5.38.2-3.2ubuntu0.4 | [perl-modules-5.38 5.38.2-3.2ubuntu0.4](https://patchblox.com/security/data/fix/linux/ubuntu-noble-perl-modules-5.38-5.38.2-3.2ubuntu0.4.md) | Jul 13, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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