{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-55204: HAProxy - NULL Pointer Dereference in hpack_dht_insert Function","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-55204","status":"final","version":"1","initial_release_date":"2026-06-18T16:05:52.058Z","current_release_date":"2026-06-18T17:26:38.498Z","revision_history":[{"date":"2026-06-18T16:05:52.058Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"HAProxy through  3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-55204 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-55204"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-55204"},{"category":"external","summary":"Patch Commit","url":"https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"},{"category":"external","summary":"vulncheck.com","url":"https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"}]},"product_tree":{"branches":[{"category":"vendor","name":"haproxy","branches":[{"category":"product_name","name":"haproxy","branches":[{"category":"product_version_range","name":"<=3.4.0","product":{"name":"haproxy haproxy <=3.4.0","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513","product":{"name":"haproxy haproxy 9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513","product_id":"CSAFPID-2","product_identification_helper":{"cpe":"cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-55204","title":"HAProxy - NULL Pointer Dereference in hpack_dht_insert Function","notes":[{"category":"description","text":"HAProxy through  3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1"],"fixed":["CSAFPID-2"]},"scores":[{"cvss_v4":{"version":"4.0","vectorString":"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","baseScore":8.7,"baseSeverity":"HIGH"},"products":["CSAFPID-1"]}],"remediations":[{"category":"vendor_fix","details":"Update to a fixed version: 9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513.","product_ids":["CSAFPID-1"],"url":"https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"}]}]}