# CVE-2026-6554: infinte loop in libpcap before 1.10.7

CVE-2026-6554 is fixed in 4 products on 1 platform, first by FEDORA-2026-4401B94AD0, released September 10, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-6554
- Priority: High
- CVSS: 7.5 (Moderate)
- EPSS: 0.0044
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 5, 2026
- Weakness: Loop with Unreachable Exit Condition ('Infinite Loop')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-6554

## Description

libpcap BPF interpreter treats the offset in the 'ja L' BPF instruction as a signed integer to implement looping via backward jumps, but it does not limit the number of loop iterations.  A crafted filter program or the 'protochain' primitive used on a crafted network packet can cause the interpreter to loop infinitely.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libpcap Debian 14 | 1.10.7-1 | [DEBIAN-CVE-2026-6554](https://patchblox.com/security/data/fix/linux/debian-cve-2026-6554.md) | Sep 14, 2026 |
| Linux | libpcap Fedora 43 | 14:1.10.7-1.fc43 | [FEDORA-2026-4401B94AD0](https://patchblox.com/security/data/fix/linux/fedora-2026-4401b94ad0.md) | Sep 10, 2026 |
| Linux | libpcap amzn 2023 | 14:1.10.7-1.amzn2023.0.1 | [ALAS2023-2026-3100](https://patchblox.com/security/data/fix/linux/alas2023-2026-3100.md) | Sep 28, 2026 |
| Linux | libpcap opensuse-leap 16.0 | 1.10.5-160000.5.1 | [OPENSUSE-SU-2026:21940-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21940-1.md) | Sep 23, 2026 |
| Linux | libpcap sles 15.6 | 1.10.4-150600.3.12.1 | [SUSE-SU-2026:4194-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4194-1.md) | Sep 15, 2026 |
| Linux | libpcap sles 15.7 | 1.10.5-150700.3.13.1 | [SUSE-SU-2026:4188-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4188-1.md) | Sep 15, 2026 |
| Linux | libpcap sles 16.0 | 1.10.5-160000.5.1 | [SUSE-SU-2026:23907-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23907-1.md) | Sep 23, 2026 |
| Linux | libpcap-debuginfo Fedora 43 | 14:1.10.7-1.fc43 | [FEDORA-2026-4401B94AD0](https://patchblox.com/security/data/fix/linux/fedora-2026-4401b94ad0.md) | Sep 10, 2026 |
| Linux | libpcap-debuginfo amzn 2023 | 14:1.10.7-1.amzn2023.0.1 | [ALAS2023-2026-3100](https://patchblox.com/security/data/fix/linux/alas2023-2026-3100.md) | Sep 28, 2026 |
| Linux | libpcap-debugsource Fedora 43 | 14:1.10.7-1.fc43 | [FEDORA-2026-4401B94AD0](https://patchblox.com/security/data/fix/linux/fedora-2026-4401b94ad0.md) | Sep 10, 2026 |
| Linux | libpcap-debugsource amzn 2023 | 14:1.10.7-1.amzn2023.0.1 | [ALAS2023-2026-3100](https://patchblox.com/security/data/fix/linux/alas2023-2026-3100.md) | Sep 28, 2026 |
| Linux | libpcap-devel Fedora 43 | 14:1.10.7-1.fc43 | [FEDORA-2026-4401B94AD0](https://patchblox.com/security/data/fix/linux/fedora-2026-4401b94ad0.md) | Sep 10, 2026 |
| Linux | libpcap-devel amzn 2023 | 14:1.10.7-1.amzn2023.0.1 | [ALAS2023-2026-3100](https://patchblox.com/security/data/fix/linux/alas2023-2026-3100.md) | Sep 28, 2026 |

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Data as of 2026-11-08T00:53:09Z 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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