SB2026021269 - Two denial of service vulnerabilities in haproxy QUIC parsing

Description

This security bulletin contains information about 2 vulnerabilities.

1) Infinite loop (CVE-ID: CVE-2026-26080)

CWE-ID: CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to infinite loop when handling QUIC packets. A remote attacker can consume all available system resources and cause denial of service conditions.

2) Integer underflow (CVE-ID: CVE-2026-26081)

CWE-ID: CWE-191 - Integer underflow

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform a denial of service attack.

The vulnerability exists due to integer underflow when handling QUIC packets. A remote attacker can send a specially crafted request to the server, trigger an integer underflow and perform a denial of service attack.

Remediation

Install update from vendor's website.

References

• https://www.mail-archive.com/haproxy@formilux.org/msg46589.html
• https://www.haproxy.com/blog/cves-2026-quic-denial-of-service
• https://git.haproxy.org/?p=haproxy-3.2.git;a=commit;h=5bb098ce8a656ec5711b4de3e4c87f12b216e7a1
• https://git.haproxy.org/?p=haproxy-3.0.git;a=commit;h=a05eade0f07483e6b6d0b61b1749e9093647e802
• https://git.haproxy.org/?p=haproxy-3.2.git;a=commit;h=4765277f4f915baac2d57db63538ff0a59966deb