CVE-2023-45288

CVE-2023-45288 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 92% places it in the 100th percentile, indicating an elevated likelihood of exploitation.

Key facts

Description

An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames we will process before closing a connection.

Frequently asked questions

What is CVE-2023-45288?
An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames we will process before closing a connection.
How severe is CVE-2023-45288?
CVE-2023-45288 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-2023-45288 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 92% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2023-45288?
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.
Does CVE-2023-45288 have an EU (EUVD) identifier?
Yes. CVE-2023-45288 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-1094.
When was CVE-2023-45288 published?
CVE-2023-45288 was published on 2024-04-04 and last updated on 2026-06-17.

References