What’s Vulnerable › Vulnerabilities
CVE-2021-39275: ap_escape_quotes buffer overflow
- Severity: critical (CVSS 9.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 39.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2021-09-16 · updated 2026-06-17
- Weakness: CWE-787
Description
ap_escape_quotes() may write beyond the end of a buffer when given malicious input. No included modules pass untrusted data to these functions, but third-party / external modules may. This issue affects Apache HTTP Server 2.4.48 and earlier.
Affected products
- Apache HTTP Server: before 2.4.49 — fixed in 2.4.49
- Debian Linux: 9.0, 10.0, 11.0
- Fedoraproject Fedora: 34, 35
- NetApp Cloud Backup: all versions
- Clustered Data ONTAP: all versions
- NetApp StorageGRID: all versions
- Oracle Corporation Oracle HTTP Server: 12.2.1.3.0, 12.2.1.4.0
- Oracle Instantis Enterprisetrack: 17.1, 17.2, 17.3
- Oracle Corporation Oracle ZFS Storage Appliance Kit: 8.8
- Siemens SINEC NMS: all versions
- Siemens SINEMA Server V14: 14.0
How to fix
Upgrade to a fixed version: Apache HTTP Server 2.4.49. Check the vendor advisory for mitigations.
References
- https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.apache.org/thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
- https://security.gentoo.org/glsa/202208-20
- https://security.netapp.com/advisory/ntap-20211008-0004/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ
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