BIT-haproxy-2026-55204: HAProxy - NULL Pointer Dereference in hpack_dht_insert Function
HAProxy versions prior to 3.4.1 contain a null pointer dereference vulnerability in the hpack_dht_insert() function due to improper validation of hpack_dht_defrag() return values under memory exhaustion. This flaw can be triggered by an attacker causing HPACK dynamic table insertions when memory is low, leading to a crash of HAProxy worker processes and resulting in denial of service.
AI Analysis
Technical Summary
The vulnerability in HAProxy through version 3.4.0 (fixed in commit 9a6d1fe) is a null pointer dereference in the hpack_dht_insert() function located in src/hpack-tbl.c. The issue arises because the function does not properly check the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can exploit this by triggering HPACK dynamic table insertions under memory pressure, causing a NULL pointer dereference that crashes HAProxy worker processes, leading to denial of service.
Potential Impact
Successful exploitation causes HAProxy worker processes to crash due to a null pointer dereference, resulting in denial of service. There is no indication of code execution or data disclosure. No known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade HAProxy to version 3.4.1 or later, where this vulnerability is fixed by commit 9a6d1fe. No other mitigations are indicated. Patch status is confirmed fixed in 3.4.1.
BIT-haproxy-2026-55204: HAProxy - NULL Pointer Dereference in hpack_dht_insert Function
Description
HAProxy versions prior to 3.4.1 contain a null pointer dereference vulnerability in the hpack_dht_insert() function due to improper validation of hpack_dht_defrag() return values under memory exhaustion. This flaw can be triggered by an attacker causing HPACK dynamic table insertions when memory is low, leading to a crash of HAProxy worker processes and resulting in denial of service.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in HAProxy through version 3.4.0 (fixed in commit 9a6d1fe) is a null pointer dereference in the hpack_dht_insert() function located in src/hpack-tbl.c. The issue arises because the function does not properly check the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can exploit this by triggering HPACK dynamic table insertions under memory pressure, causing a NULL pointer dereference that crashes HAProxy worker processes, leading to denial of service.
Potential Impact
Successful exploitation causes HAProxy worker processes to crash due to a null pointer dereference, resulting in denial of service. There is no indication of code execution or data disclosure. No known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade HAProxy to version 3.4.1 or later, where this vulnerability is fixed by commit 9a6d1fe. No other mitigations are indicated. Patch status is confirmed fixed in 3.4.1.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- BIT-haproxy-2026-55204
- Osv Schema Version
- 1.6.2
- Aliases
- ["CVE-2026-55204"]
- Ecosystems
- ["Bitnami"]
- Database Specific Severity
- High
- Cvss Version
- null
Threat ID: 6a42ed7327e9c79719939236
Added to database: 06/29/2026, 22:10:59 UTC
Last enriched: 06/29/2026, 22:38:22 UTC
Last updated: 06/29/2026, 22:38:22 UTC
Views: 2
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