How severe is CVE-2026-28780?

CVE-2026-28780 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-28780 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28780?

CVE-2026-28780 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28780?

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

Does CVE-2026-28780 have an EU (EUVD) identifier?

Yes. CVE-2026-28780 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27506.

When was CVE-2026-28780 published?

CVE-2026-28780 was published on 2026-05-05 and last updated on 2026-06-30.

CVE-2026-28780

CVE-2026-28780 is a critical-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 9.8. 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-122.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27506
Weakness: CWE-122
Affected product: Apache Http Server
Published: 2026-05-05
Last modified: 2026-06-30

Description

Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Frequently asked questions

What is CVE-2026-28780?: Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.
How severe is CVE-2026-28780?: CVE-2026-28780 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-28780 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28780?: CVE-2026-28780 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28780?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-28780 have an EU (EUVD) identifier?: Yes. CVE-2026-28780 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27506.
When was CVE-2026-28780 published?: CVE-2026-28780 was published on 2026-05-05 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

50.255.62.89 (ipv4-addr)
147.15.15.226 (ipv4-addr)
45.84.120.3 (ipv4-addr)
79.137.34.248 (ipv4-addr)
77.90.185.88 (ipv4-addr)
77.90.185.87 (ipv4-addr)
74.87.117.150 (ipv4-addr)
50.35.168.148 (ipv4-addr)