Home/CVE/In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a
CVE

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

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.

CRITICAL · CVSS 9.8 EPSS 0.47816
Schedule remediation
  • EPSS ≥ 0.10 - elevated exploitation probability
  • EPSS percentile: top 2% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

8
apache http server>= 2.4.0 and <= 2.4.46
debian linuxall versions
fedoraproject fedoraall versions
oracle enterprise manager ops centerall versions
oracle instantis enterprisetrackall versions
oracle secure backup< 18.1.0.1.0
oracle zfs storage appliance kitall versions
netapp cloud backupall versions
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security@apache.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD10 Jun 2021 · 07:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
⚑

Vendor Advisories

15
rhsaRHSA-2022:0143Important
rhsaRHSA-2021:4537Important
rhsaRHSA-2021:3816Important
rhsaRHSA-2021:4614Moderate
rhsaRHSA-2021:4613Moderate
🔗

References & Sources

13
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
http://httpd.apache.org/security/vulnerabilities_24.htmlVendor Advisory
http://www.openwall.com/lists/oss-security/2021/06/10/7Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/r50cae1b71f1e7421069036b213c26da7d8f47dd59874e3bd956959fe%40%3Cannounce.httpd.apache.org%3E
https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E
https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3EMailing ListRelease NotesVendor Advisory
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.htmlMailing ListThird Party Advisory
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