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CVE-2021-39275— ap_escape_quotes buffer overflow

Quick assessment

Affected

Apache Software Foundation Apache HTTP Server

Exploitation

High exploitation probability; assess promptly

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Apache HTTP Server是美国阿帕奇（Apache）基金会的一款开源网页服务器。该服务器具有快速、可靠且可通过简单的API进行扩充的特点。 Apache HTTP Server 2.4.48及之前版本存在缓冲区错误漏洞，该漏洞源于当给定恶意输入时，ap_escape_quotes（）可能会写入缓冲区之外的内容。

AI Predicted 7.5 Difficulty: Moderate EPSS 39.40% · P99 Updated Feb 25, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

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I. Basic Information for CVE-2021-39275

Vulnerability Information

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Vulnerability Title

ap_escape_quotes buffer overflow

Source: CVE Program / CVE List V5

Vulnerability 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.

Source: CVE Program / CVE List V5

CVSS Information

N/A

Source: CVE Program / CVE List V5

Vulnerability Type

N/A

Source: CVE Program / CVE List V5

Vulnerability Title

Apache HTTP Server 缓冲区错误漏洞

Source: CNNVD (China National Vulnerability Database)

Vulnerability Description

Source: CNNVD (China National Vulnerability Database)

CVSS Information

N/A

Source: CNNVD (China National Vulnerability Database)

Vulnerability Type

N/A

Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Apache Software Foundation	Apache HTTP Server	Apache HTTP Server 2.4 ~ 2.4.48	-

II. Public POCs for CVE-2021-39275

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2021-39275

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Vendor Advisories for CVE-2021-39275 (8)

https://www.oracle.com/security-alerts/cpujan2022.html x_refsource_MISC
https://security.netapp.com/advisory/ntap-20211008-0004/ x_refsource_CONFIRM
Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project x_refsource_MISC
https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf x_refsource_CONFIRM
https://www.oracle.com/security-alerts/cpuapr2022.html x_refsource_MISC
https://www.debian.org/security/2021/dsa-4982 vendor-advisory x_refsource_DEBIAN
🔗 Apache HTTPD: Multiple Vulnerabilities (GLSA 202208-20) — Gentoo security Read full article vendor-advisory x_refsource_GENTOO
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ vendor-advisory x_refsource_CISCO

Mailing List Discussions for CVE-2021-39275 (5)

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/ vendor-advisory x_refsource_FEDORA
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/ vendor-advisory x_refsource_FEDORA
https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E mailing-list x_refsource_MLIST
https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html mailing-list x_refsource_MLIST
https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E mailing-list x_refsource_MLIST

https://www.cve.org/CVERecord?id=CVE-2021-39275

Same Patch Batch · Apache Software Foundation · 2021-09-16 · 6 CVEs total

CVE-2021-41079		Apache Tomcat DoS with unexpected TLS packet
CVE-2021-40438		mod_proxy SSRF
CVE-2021-39239		XML External Entity (XXE) vulnerability
CVE-2021-36160		mod_proxy_uwsgi out of bound read
CVE-2021-34798		NULL pointer dereference in httpd core

IV. Related Vulnerabilities

Same product: Apache HTTP Server

Same vendor: Apache Software Foundation

V. Comments for CVE-2021-39275

No comments yet

Goal Reached Thanks to every supporter — we hit 100%!

CVE-2021-39275— ap_escape_quotes buffer overflow

Quick assessment

Possible ATT&CK Techniques 1 AI

I. Basic Information for CVE-2021-39275

Vulnerability Information

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Affected Products

II. Public POCs for CVE-2021-39275

III. Intelligence Information for CVE-2021-39275

Vendor Advisories for CVE-2021-39275 (8)

Mailing List Discussions for CVE-2021-39275 (5)

Same Patch Batch · Apache Software Foundation · 2021-09-16 · 6 CVEs total

IV. Related Vulnerabilities

V. Comments for CVE-2021-39275

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