CVE-2026-54428 | Apache HttpComponents Core: HPackDecoder Unlimited Header List Size Before SETTINGS ACK

Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2 SETTINGS acknowledgement causes the configured header list size limit to be applied.

Published: 2026-07-01 Last update: 2026-07-06 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-54428 is rated Moderate Risk (45.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.59%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-54428

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-07 0.41% 0.59% +0.18%
2 2026-07-02 — 0.41% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-54428

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-54428

GitHub Security Advisory for CVE-2026-54428

GHSA-v3jc-474w-2wm6 · Severity: high — Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache...

OS Trackers for CVE-2026-54428

vendor priority summary link
debian not yet assigned CVE-2026-54428 not yet assigned priority: Debian including 2 source packages (httpcomponents-core, httpcomponents-core5), 9 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 9. https://security-tracker.debian.org/tracker/CVE-2026-54428
ubuntu medium CVE-2026-54428 medium priority: Ubuntu including 2 source packages (httpcomponents-core, httpcomponents-core5), 13 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream): needs-triage 13. https://ubuntu.com/security/CVE-2026-54428

Affected software / configurations for CVE-2026-54428

Vendor Product Version Raw CPE
apache httpcomponents_core <= 5.4.2 cpe:2.3:a:apache:httpcomponents_core:*:*:*:*:*:*:*:*
apache httpcomponents_core 5.5 cpe:2.3:a:apache:httpcomponents_core:5.5:alpha1:*:*:*:*:*:*
apache httpcomponents_core 5.5 cpe:2.3:a:apache:httpcomponents_core:5.5:beta1:*:*:*:*:*:*

References for CVE-2026-54428

cvelogic Threat Intelligence