CVE-2021-41524
null pointer dereference in h2 fuzzing
- Published
- Updated
- Reserved
- Assigned by
- apache
Description
While fuzzing the 2.4.49 httpd, a new null pointer dereference was detected during HTTP/2 request processing, allowing an external source to DoS the server. This requires a specially crafted request. The vulnerability was recently introduced in version 2.4.49. No exploit is known to the project.
Timeline
ID reserved
By apache
- 15 days later
· 15 days later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 25.8% · top 2.0% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
Apache Software Foundation · Apache HTTP Server
- affected 2.4.49
What to do
Workaround: Disable the HTTP/2 protocol.
References (8)
- https://httpd.apache.org/security/vulnerabilities_24.html (opens in a new tab)x_refsource_MISCx_transferred
- [oss-security] 20211005 CVE-2021-41524: Apache HTTP Server: null pointer dereference in h2 fuzzing (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- FEDORA-2021-5d2d4b6ac5 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- 20211007 Apache HTTP Server Vulnerabilties: October 2021 (opens in a new tab)vendor-advisoryx_refsource_CISCOx_transferred
- FEDORA-2021-f94985afca (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- https://www.oracle.com/security-alerts/cpujan2022.html (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20211029-0009/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- GLSA-202208-20 (opens in a new tab)vendor-advisoryx_refsource_GENTOOx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-41524)Record last updated .