Buffer overflow in Apache HTTP Server
CVE-2021-26691
In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.683 (99.3th percentile), scored .
High probability of exploitation in the next 30 days — patch promptly. 99th percentile — 99.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.683 · newest: 0.683 · change: 0.000
Affected products
- Apache HTTP Server
- Apache Software Foundation HTTP Server — versions 2.4.46, 2.4.43, 2.4.41
- NetApp Cloud Backup
- Oracle Enterprise Manager Ops Center — versions 12.4.0.0
- Oracle Instantis Enterprisetrack — versions 17.1, 17.2, 17.3
- Oracle Secure Backup
- Oracle Zfs Storage Appliance Kit — versions 8.8
- Debian Linux — versions 9.0, 10.0
- Fedoraproject Fedora — versions 34, 35
Weakness classification (CWE)
Public proof-of-concept exploits
References
- httpd.apache.org/security/vulnerabilities_24.html (Vendor Advisory)
- lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cb… (Mailing List, Release Notes, Vendor Advisory)
- lists.apache.org/thread.html/r50cae1b71f1e7421069036b213c26da7d8f47dd59874e3bd9… (mailing-list)
- lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cd… (mailing-list)
- www.openwall.com/lists/oss-security/2021/06/10/7 (mailing-list, Mailing List, Third Party Advisory)
- lists.debian.org/debian-lts-announce/2021/07/msg00006.html (mailing-list, Mailing List, Third Party Advisory)
- www.debian.org/security/2021/dsa-4937 (vendor-advisory, Mailing List, Third Party Advisory)
- security.gentoo.org/glsa/202107-38 (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2021-26691?
- CVE-2021-26691 is a critical-severity vulnerability in Apache HTTP Server, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2021-06-10.
- How severe is CVE-2021-26691?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2021-26691 known to be exploited?
- 23 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.