CVE-2021-39275

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 36%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
98.3%
KEV
Not listed

Published

September 16, 2021

Last Modified

May 1, 2025

Advisory Details (9)

Auto-updated Jun 21, 2026
⚠️ Active exploitation confirmed. Patch available.
generic

Apache HTTPD: Multiple Vulnerabilities (GLSA 202208-20) — Gentoo security

https://security.gentoo.org/glsa/202208-20
generic

[SECURITY] Fedora 35 Update: httpd-2.4.49-1.fc35 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
generic

[SECURITY] Fedora 34 Update: httpd-2.4.49-1.fc34 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
generic Patch Available

[SECURITY] [DLA 2776-1] apache2 security update

https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html
generic
https://lists.apache.org/thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E
generic
https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E
generic
https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E
generic
https://lists.apache.org/thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E
generic Patch Available🔴 Active Exploitation

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

https://httpd.apache.org/security/vulnerabilities_24.html

Vendor Advisories for CVE-2021-39275(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(7)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuapache2-utils (2.4.18-2ubuntu3.17+esm2) @ xenial2026-05-26ubuntu
ubuntuapache2-bin (2.4.46-4ubuntu1.2) @ hirsute2026-05-26ubuntu
redhatjbcs-httpd24-httpd2022-10-26redhat
redhatjbcs-httpd24-httpd-0:2.4.51-28.el7jbcs2022-10-26redhat
redhathttpd24-httpd-0:2.4.34-23.el7.52022-09-29redhat
redhathttpd:2.4-8050020220228164203.c53685002022-03-15redhat
redhathttpd-0:2.4.6-97.el7_9.42022-01-17redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(6)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 12× in last 7d / 35× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-16 17:00 UTCEPSS rescore
  2. 2026-07-16 17:00 UTCEPSS rescore
  3. 2026-07-15 16:55 UTCEPSS rescore
  4. 2026-07-15 16:55 UTCEPSS rescore
  5. 2026-07-15 01:58 UTCEPSS rescore
  6. 2026-07-13 22:27 UTCEPSS rescore
  7. 2026-07-13 22:27 UTCEPSS rescore
  8. 2026-07-13 06:11 UTCEPSS rescore
  9. 2026-07-13 06:11 UTCEPSS rescore
  10. 2026-07-12 05:44 UTCEPSS rescore
  11. 2026-07-11 08:25 UTCEPSS rescore
  12. 2026-07-11 08:25 UTCEPSS rescore
  13. 2026-07-09 19:07 UTCEPSS rescore
  14. 2026-07-06 16:25 UTCEPSS rescore
  15. 2026-07-06 16:25 UTCEPSS rescore
  16. 2026-07-05 02:28 UTCEPSS rescore
  17. 2026-07-05 02:28 UTCEPSS rescore
  18. 2026-07-02 16:57 UTCEPSS rescore
  19. 2026-07-01 15:04 UTCEPSS rescore
  20. 2026-06-30 13:30 UTCOSV refresh
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-28 04:54 UTCEPSS rescore
  23. 2026-06-27 03:06 UTCEPSS rescore
  24. 2026-06-27 03:06 UTCEPSS rescore
  25. 2026-06-25 13:48 UTCEPSS rescore
Show 54 more
  1. 2026-06-25 13:48 UTCEPSS rescore
  2. 2026-06-24 14:03 UTCEPSS rescore
  3. 2026-06-24 14:03 UTCEPSS rescore
  4. 2026-06-23 21:31 UTCEPSS rescore
  5. 2026-06-23 21:31 UTCEPSS rescore
  6. 2026-06-21 01:58 UTCEPSS rescore
  7. 2026-06-21 01:58 UTCEPSS rescore
  8. 2026-06-18 17:51 UTCEPSS rescore
  9. 2026-06-18 17:51 UTCEPSS rescore
  10. 2026-06-17 17:51 UTCEPSS rescore
  11. 2026-06-16 17:51 UTCEPSS rescore
  12. 2026-06-16 17:51 UTCEPSS rescore
  13. 2026-06-15 17:46 UTCEPSS rescore
  14. 2026-06-14 23:15 UTCEPSS rescore
  15. 2026-06-13 22:58 UTCEPSS rescore
  16. 2026-06-13 22:58 UTCEPSS rescore
  17. 2026-06-12 23:10 UTCEPSS rescore
  18. 2026-06-12 23:10 UTCEPSS rescore
  19. 2026-06-12 21:10 UTCOSV refresh
  20. 2026-06-11 13:58 UTCEPSS rescore
  21. 2026-06-10 22:16 UTCEPSS rescore
  22. 2026-06-10 13:20 UTCEPSS rescore
  23. 2026-06-08 14:15 UTCEPSS rescore
  24. 2026-06-08 14:15 UTCEPSS rescore
  25. 2026-06-07 15:23 UTCEPSS rescore
  26. 2026-06-07 15:23 UTCEPSS rescore
  27. 2026-06-06 13:46 UTCEPSS rescore
  28. 2026-06-06 13:46 UTCEPSS rescore
  29. 2026-06-06 13:46 UTCEPSS rescore
  30. 2026-06-05 22:45 UTCEPSS rescore
  31. 2026-06-05 06:09 UTCEPSS rescore
  32. 2026-06-05 06:09 UTCEPSS rescore
  33. 2026-06-04 13:10 UTCEPSS rescore
  34. 2026-06-04 13:10 UTCEPSS rescore
  35. 2026-06-02 20:11 UTCEPSS rescore
  36. 2026-06-02 20:11 UTCEPSS rescore
  37. 2026-05-31 22:29 UTCEPSS rescore
  38. 2026-05-31 22:29 UTCEPSS rescore
  39. 2026-05-31 00:15 UTCEPSS rescore
  40. 2026-05-31 00:15 UTCEPSS rescore
  41. 2026-05-29 13:42 UTCEPSS rescore
  42. 2026-05-29 13:42 UTCEPSS rescore
  43. 2026-05-28 13:43 UTCEPSS rescore
  44. 2026-05-28 13:43 UTCEPSS rescore
  45. 2026-05-27 13:39 UTCEPSS rescore
  46. 2026-05-27 13:39 UTCEPSS rescore
  47. 2026-05-27 13:39 UTCEPSS rescore
  48. 2026-05-26 13:42 UTCEPSS rescore
  49. 2026-05-26 10:17 UTCEG score recompute
  50. 2026-05-26 10:17 UTCVendor advisory
  51. 2026-05-26 10:17 UTCGHSA enrichment
  52. 2026-05-26 07:17 UTCEPSS rescore
  53. 2026-05-26 07:17 UTCEPSS rescore
  54. 2026-05-26 07:17 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-39275?
CVE-2021-39275 is a critical vulnerability published on September 16, 2021. apescapequotes() 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.
When was CVE-2021-39275 disclosed?
CVE-2021-39275 was first published in the National Vulnerability Database on September 16, 2021, with the most recent update on May 1, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-39275 actively exploited?
CVE-2021-39275 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 98.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-39275?
CVE-2021-39275 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-39275?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-39275, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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