CVE-2026-55204High· 7.5▾ TwilightHAProxy 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 exhaust…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Oct 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.5%
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.
haproxy < 2.4.36haproxy >= 2.5, < 2.6.30haproxy >= 2.7, < 2.8.25haproxy >= 2.9, < 3.0.24haproxy >= 3.1, < 3.2.20haproxy >= 3.3, < 3.4.1Upgrade past the affected range:
haproxy 3.4.1Connected by shared product, vendor, weakness, or advisory.
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