# CVE-2026-66337: libsoup: A flaw was found in libsoup

CVE-2026-66337 is fixed in 10 products on 1 platform, first by ALAS2023-2026-3212, released November 7, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-66337
- Priority: High
- CVSS: n/a (important)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 12, 2026

## Description

A flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_read_until() function causes a heap buffer over-read when parsing multipart HTTP responses. A malicious HTTP server can exploit this by sending a crafted multipart response, potentially causing the client application to crash or disclose sensitive heap memory.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libsoup amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-debuginfo amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-debugsource amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-devel amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup-doc amzn 2023 | 2.72.0-6.amzn2023.0.16 | [ALAS2023-2026-3212](https://patchblox.com/security/data/fix/linux/alas2023-2026-3212.md) | Nov 7, 2026 |
| Linux | libsoup3 amzn 2023 | 3.7.3-1.amzn2023 | [ALAS2023-2026-3240](https://patchblox.com/security/data/fix/linux/alas2023-2026-3240.md) | Nov 7, 2026 |
| Linux | libsoup3-debuginfo amzn 2023 | 3.7.3-1.amzn2023 | [ALAS2023-2026-3240](https://patchblox.com/security/data/fix/linux/alas2023-2026-3240.md) | Nov 7, 2026 |
| Linux | libsoup3-debugsource amzn 2023 | 3.7.3-1.amzn2023 | [ALAS2023-2026-3240](https://patchblox.com/security/data/fix/linux/alas2023-2026-3240.md) | Nov 7, 2026 |
| Linux | libsoup3-devel amzn 2023 | 3.7.3-1.amzn2023 | [ALAS2023-2026-3240](https://patchblox.com/security/data/fix/linux/alas2023-2026-3240.md) | Nov 7, 2026 |
| Linux | libsoup3-doc amzn 2023 | 3.7.3-1.amzn2023 | [ALAS2023-2026-3240](https://patchblox.com/security/data/fix/linux/alas2023-2026-3240.md) | Nov 7, 2026 |

---

Data as of 2026-11-11T13:47:35Z 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

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.