CVE-2026-33555

mediumpriority · track · 33EPSS 0.003 · 23 %ileexploit · PoCDEEURUUS
grimoire priorityP1 · Urgent
Exploitable?
Public exploit
1 exploit · PoC
Likely / severe?
0.31% (23rd) EPSS
CVSS 5.8 · medium
Is it mine?
21 products
Check your exposure
Who says so?
6 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

5.8
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.8mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 1.4
v3.15.8mediumAV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:Nsecondary · FSTEC (BDU) RU
v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:Nsecondary · ENISA EU
v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:Nsecondary · cve@mitre.org USexploitability 2.2 · impact 1.4
v3.15.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:Psecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-130USCWE-130USCWE-130US
04

exploits (1)

Public proof-of-concept and weaponised exploit code.

05

affected products (21)

Products and version ranges known to be affected.

showing 20 of 21
06

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-1074HAProxy: Schwachstelle ermöglicht Manipulation von DateienDeutsch2026-04-13csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann eine Schwachstelle in HAProxy ausnutzen, um Dateien zu manipulieren.

  • BIT-haproxy-2026-335552026-06-30vendor · osvUS

    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.

07

also known as (5)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundnvdosvNVDCVE.orgMITRE
published 2026-04-13modified 2026-10-18
09

references (16)

External citations — patches, advisories, analysis.

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