How severe is CVE-2026-54399?

CVE-2026-54399 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-54399 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-54399?

CVE-2026-54399 primarily affects Apache Httpcomponents Core. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-54399?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-54399 published?

CVE-2026-54399 was published on 2026-07-01 and last updated on 2026-07-06.

CVE-2026-54399

CVE-2026-54399 is a high-severity vulnerability in Apache Httpcomponents Core with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Apache Httpcomponents Core
Published: 2026-07-01
Last modified: 2026-07-06

Description

Uncontrolled Resource Consumption vulnerability in the HTTP/1.1 message parser 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 messages with excessive number of headers / excessive header length

Frequently asked questions

What is CVE-2026-54399?: Uncontrolled Resource Consumption vulnerability in the HTTP/1.1 message parser 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 messages with excessive number of headers / excessive header length
How severe is CVE-2026-54399?: CVE-2026-54399 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-54399 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-54399?: CVE-2026-54399 primarily affects Apache Httpcomponents Core. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-54399?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-54399 published?: CVE-2026-54399 was published on 2026-07-01 and last updated on 2026-07-06.

References

Affected products (3)

cpe:2.3:a:apache:httpcomponents_core:*:*:*:*:*:*:*:*
cpe:2.3:a:apache:httpcomponents_core:5.5:alpha1:*:*:*:*:*:*
cpe:2.3:a:apache:httpcomponents_core:5.5:beta1:*:*:*:*:*:*

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