CVE-2026-26080: HAProxy Community Edition 3.2.x through 3.3.x before 3.3.3 can enter a loop or crash because varint is mishandled. HAProxy Enterprise and ALOHA are also affected.

lowCVSS 3.7CVE-2026-26080

CSIRTS triage

vendor: HAProxy product: HAProxy Community Edition Denial of serviceaffected: 3.2.x through 3.3.x before 3.3.3

What: HAProxy can enter a loop or crash due to mishandling of varint.
Who is affected: Users of HAProxy Community Edition versions 3.2.x to 3.3.x before 3.3.3.
Urgency: Low urgency as the CVSS score is 3.7, indicating low severity.
Action: Upgrade to HAProxy version 3.3.3 or later.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: low — CVSS 3.7
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26080

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-260800.42% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 34% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-26080	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for HAProxy Community Edition

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-26081: HAProxy Community Edition 3.0 through 3.3 before 3.3.3 lacks a length check for the NEW_TOKEN …nvd · 2026-07-20
lowCVE-2026-26080: HAProxy Community Edition 3.2.x through 3.3.x before 3.3.3 can enter a loop or crash because v…nvd · 2026-07-20
mediumCVE-2026-26081: HAProxy Community Edition 3.0 through 3.3 before 3.3.3 lacks a length check for the NEW_TOKEN …msrc · 2026-07-14