Loading vulnerability…
CVE-2026-55203 is an integer overflow vulnerability in HAProxy's FastCGI record handling, affecting versions through 3.4.0. The drl field in the fcgi_conn structure wraps to zero when contentLength is 65535 and paddingLength is at least 1. Incorrect record consumption then allows buffered data to be misinterpreted as new FastCGI record headers. A malicious FastCGI backend can exploit this behavior to desynchronize the framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A critical network-accessible vulnerability tracked as CVE-2026-55203, covered by a Rocky Linux 9.6 local security check. The provided CVSS vectors indicate no required privileges or user interaction, with high integrity impact and availability impact; the underlying affected component is not identified in the content.
A vulnerability addressed by the Huawei EulerOS SA-2026-3267 update for EulerOS 2.0 HAProxy-related packages. The supplied CVSS v3 vector indicates unauthenticated network exploitation with high integrity and availability impact.
A vulnerability addressed by Huawei EulerOS advisory SA-2026-3342 affecting HAProxy-related packages on EulerOS 2.0. The supplied CVSS vectors indicate network-reachable impact to integrity and availability.
A remotely exploitable HAProxy vulnerability affecting the HAProxy package on Alibaba Cloud Linux 3. The supplied CVSS v3 vector indicates network-reachable exploitation without privileges or user interaction, with high integrity and availability impact.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.