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01 Record

CVE-2023-43622

Apache HTTP Server: DoS in HTTP/2 with initial windows size 0

UnratedPUBLISHEDCNA: apache
CNA base scoreUnratedNo CNA CVSS vector

02 Description

Apache HTTP Server: DoS in HTTP/2 with initial windows size 0

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
68.81% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 99.3% of scored records. A rank, not a probability.
NVD base score
7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2023-10-23 06:50Z3 YR AGO
Last updated
2025-02-13 17:13Z1 YR AGO
Reserved
2023-09-20
Assigning CNA
apache
Record state
PUBLISHED
Severity
Not rated by the issuing CNA
CNA CVSS vector
Not published by the issuing CNA
Weaknesses
  • CWE-400Uncontrolled Resource ConsumptionClass
Data version
5.1
Document digest
6a49c60eba488ad4ce4bda538719e2c06cebf0f66da69e681197cafd4d161400

05 Affected products

VendorProductVersionsPlatforms
Apache Software FoundationApache HTTP Server2.4.55 to 2.4.57—

06 References

07 Fixed in

AlmaLinux 9

  • mod_http2
    Fixed in 2.0.26-1.el9

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • mod_http2
    Fixed in 2.0.26-1.el9

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • apache2
    Fixed in 2.4.59-1~deb12u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • apache2
    Fixed in 2.4.58-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • apache2
    Fixed in 2.4.58-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.