libsoup: A flaw was found in libsoup
CVE-2026-66338 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.
A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| libsoup · amzn 2023 | 2.72.0-6.amzn2023.0.16 | ALAS2023-2026-3212 | Nov 7, 2026 |
| libsoup-debuginfo · amzn 2023 | 2.72.0-6.amzn2023.0.16 | ALAS2023-2026-3212 | Nov 7, 2026 |
| libsoup-debugsource · amzn 2023 | 2.72.0-6.amzn2023.0.16 | ALAS2023-2026-3212 | Nov 7, 2026 |
| libsoup-devel · amzn 2023 | 2.72.0-6.amzn2023.0.16 | ALAS2023-2026-3212 | Nov 7, 2026 |
| libsoup-doc · amzn 2023 | 2.72.0-6.amzn2023.0.16 | ALAS2023-2026-3212 | Nov 7, 2026 |
| libsoup3 · amzn 2023 | 3.7.3-1.amzn2023 | ALAS2023-2026-3240 | Nov 7, 2026 |
| libsoup3-debuginfo · amzn 2023 | 3.7.3-1.amzn2023 | ALAS2023-2026-3240 | Nov 7, 2026 |
| libsoup3-debugsource · amzn 2023 | 3.7.3-1.amzn2023 | ALAS2023-2026-3240 | Nov 7, 2026 |
| libsoup3-devel · amzn 2023 | 3.7.3-1.amzn2023 | ALAS2023-2026-3240 | Nov 7, 2026 |
| libsoup3-doc · amzn 2023 | 3.7.3-1.amzn2023 | ALAS2023-2026-3240 | Nov 7, 2026 |
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