PatchTheCVECVE-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 mishand
29
Routine
LOW 3.7REMOTEUPGRADEUPGRADEDOWNGRADE
CVE-2026-26080 is a low-severity flaw (CVSS 3.7) affecting haproxy, aloha, haproxy enterprise. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 3.7 (Low) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 54%) |
| CISA exploited list | No |
| Weakness | CWE-252 |
| Published | 2026-07-20 |
| Last modified | 2026-08-25 |
Last updated 2026-08-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
haproxy haproxy UPGRADE
Affected: >= 3.2 and < 3.2.12 · >= 3.3 and < 3.3.3
Fixed in: 3.2.12, 3.3.3
Safe to downgrade to: a release before 3.2
1. Check installed version
apt-cache policy haproxy || rpm -q haproxy || haproxy --version
2. UPGRADE to 3.2.12 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade haproxy
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade haproxy
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 3.2 (Debian / Ubuntu)
apt-cache madison haproxy
sudo apt install haproxy=<VERSION_BEFORE_3.2>
sudo apt-mark hold haproxy
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list haproxy
sudo dnf downgrade haproxy-<VERSION_BEFORE_3.2>
sudo dnf versionlock add haproxy
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
haproxy aloha UPGRADE
Affected: >= 17.0.0 and < 17.0.18 · >= 17.5.0 and < 17.5.16
Fixed in: 17.0.18, 17.5.16
Safe to downgrade to: a release before 17.0.0
1. Check installed version
apt-cache policy aloha || rpm -q aloha || aloha --version
2. UPGRADE to 17.0.18 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade aloha
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade aloha
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 17.0.0 (Debian / Ubuntu)
apt-cache madison aloha
sudo apt install aloha=<VERSION_BEFORE_17.0.0>
sudo apt-mark hold aloha
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list aloha
sudo dnf downgrade aloha-<VERSION_BEFORE_17.0.0>
sudo dnf versionlock add aloha
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
haproxy haproxy enterprise DOWNGRADE
Affected: 3.2r1 1.0.0-353.334 · 3.2r1 1.0.0-353.336 · 3.2r1 1.0.0-353.347 · 3.2r1 1.0.0-353.355 · 3.2r1 1.0.0-353.376 · 3.2r1 1.0.0-353.385 · 3.2r1 1.0.0-353.398 · 3.2r1 1.0.0-354.402
Fixed in: no fixed release known
Safe to downgrade to: a release before 3.2r1
1. Check installed version
apt-cache policy haproxy-enterprise || rpm -q haproxy-enterprise || haproxy-enterprise --version
2. No fixed release: DOWNGRADE to a release before 3.2r1 (Debian / Ubuntu)
apt-cache madison haproxy-enterprise
sudo apt install haproxy-enterprise=<VERSION_BEFORE_3.2r1>
sudo apt-mark hold haproxy-enterprise
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list haproxy-enterprise
sudo dnf downgrade haproxy-enterprise-<VERSION_BEFORE_3.2r1>
sudo dnf versionlock add haproxy-enterprise
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-26080?
haproxy: upgrade to 3.2.12, 3.3.3; aloha: upgrade to 17.0.18, 17.5.16; haproxy enterprise: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-26080 being exploited?
CVE-2026-26080 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-26080 affect?
CVE-2026-26080 affects haproxy, aloha, haproxy enterprise. Severity is low (CVSS 3.7). 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.
How urgent is CVE-2026-26080?
Priority 29/100. Remotely exploitable, no login, no user action
Software pages
Related CVEs
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- CVE-2026-26081 MEDIUM 4.8 UPGRADE UPGRADE HAProxy Community Edition 3.0 through 3.3 before 3.3.3 lacks a length check for the NEW_TOKEN format