Medium severity4.0NVD Advisory· Published Apr 13, 2026· Updated Jun 29, 2026
CVE-2026-33555
CVE-2026-33555
Description
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
14- osv-coords11 versionspkg:apk/chainguard/haproxy-2.6pkg:apk/chainguard/haproxy-2.8pkg:apk/chainguard/haproxy-3.0pkg:apk/chainguard/haproxy-3.2pkg:apk/wolfi/haproxy-3.2pkg:bitnami/haproxypkg:rpm/opensuse/haproxy&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/haproxy&distro=openSUSE%20Tumbleweedpkg:rpm/suse/haproxy&distro=SUSE%20Linux%20Enterprise%20High%20Availability%20Extension%2015%20SP6pkg:rpm/suse/haproxy&distro=SUSE%20Linux%20Enterprise%20High%20Availability%20Extension%2015%20SP7pkg:rpm/suse/haproxy&distro=SUSE%20Linux%20Micro%206.2
< 2.6.31-r0+ 10 more
- (no CPE)range: < 2.6.31-r0
- (no CPE)range: < 2.8.26-r0
- (no CPE)range: < 3.0.19-r0
- (no CPE)range: < 3.2.15-r0
- (no CPE)range: < 3.2.15-r0
- (no CPE)range: >= 2.6.0, < 3.3.6
- (no CPE)range: < 3.2.15+git64.0fc44b458-160000.2.1
- (no CPE)range: < 3.3.6+git91.af5637e93-1.1
- (no CPE)range: < 2.8.11+git0.01c1056a4-150600.3.12.1
- (no CPE)range: < 2.8.11+git0.01c1056a4-150600.3.12.1
- (no CPE)range: < 3.2.15+git64.0fc44b458-160000.2.1
Patches
Vulnerability mechanics
References
5- github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84nvdPatch
- r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.htmlnvdExploitThird Party Advisory
- www.haproxy.com/documentation/haproxy-aloha/changelog/nvdRelease Notes
- www.haproxy.orgnvdProduct
- www.mail-archive.com/[email protected]/msg46752.htmlnvdRelease Notes
News mentions
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