CVE-2026-45372

CRITICALNVD 9.99.9—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.9 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
9.9
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.9Exploit: NoneExposed: 0

A fix is available — apply it.

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (is_field_value) is run before decoding, so encoded %0D%0A passes the check and is then expanded to a literal \r\n byte pair inside the stored header value. This vulnerability is fixed in 0.44.0.

CVSS v3
9.9
EG Score
9.9(medium)
EG Risk
—
EPSS
21.6%
KEV
Not listed

Published

May 29, 2026

Last Modified

July 22, 2026

Advisory Details (1)

Auto-updated Jul 22, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection · Advisory · yhirose/cpp-httplib · GitHub

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibcpp-httplib0.18 (0.18.7-1ubuntu0.25.10.2) @ questing2026-07-16ubuntu

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.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 6× in last 7d / 68× 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.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-20 17:08 UTCEPSS rescore
  3. 2026-07-19 14:31 UTCEPSS rescore
  4. 2026-07-19 02:29 UTCEPSS rescore
  5. 2026-07-18 10:04 UTCEPSS rescore
  6. 2026-07-16 17:03 UTCEPSS rescore
  7. 2026-07-16 01:50 UTCVendor advisory
  8. 2026-07-15 16:57 UTCEPSS rescore
  9. 2026-07-15 02:00 UTCEPSS rescore
  10. 2026-07-13 22:30 UTCEPSS rescore
  11. 2026-07-13 06:13 UTCEPSS rescore
  12. 2026-07-12 05:46 UTCEPSS rescore
  13. 2026-07-12 01:10 UTCVendor advisory
  14. 2026-07-11 21:15 UTCVendor advisory
  15. 2026-07-11 17:24 UTCVendor advisory
  16. 2026-07-11 08:27 UTCEPSS rescore
  17. 2026-07-09 19:10 UTCEPSS rescore
  18. 2026-07-08 22:42 UTCVendor advisory
  19. 2026-07-07 13:46 UTCEPSS rescore
  20. 2026-07-06 16:27 UTCEPSS rescore
  21. 2026-07-06 02:23 UTCEPSS rescore
  22. 2026-07-05 02:30 UTCEPSS rescore
  23. 2026-07-04 06:31 UTCEPSS rescore
  24. 2026-07-02 23:01 UTCVendor advisory
  25. 2026-07-02 19:00 UTCVendor advisory
Show 75 more
  1. 2026-07-02 12:50 UTCVendor advisory
  2. 2026-07-02 08:10 UTCVendor advisory
  3. 2026-07-02 03:52 UTCVendor advisory
  4. 2026-07-01 20:32 UTCVendor advisory
  5. 2026-07-01 16:44 UTCVendor advisory
  6. 2026-07-01 15:07 UTCEPSS rescore
  7. 2026-07-01 12:25 UTCVendor advisory
  8. 2026-07-01 08:37 UTCVendor advisory
  9. 2026-07-01 01:28 UTCVendor advisory
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-30 09:25 UTCVendor advisory
  12. 2026-06-30 05:37 UTCVendor advisory
  13. 2026-06-30 00:53 UTCVendor advisory
  14. 2026-06-29 20:07 UTCVendor advisory
  15. 2026-06-29 16:19 UTCVendor advisory
  16. 2026-06-29 12:31 UTCVendor advisory
  17. 2026-06-29 02:05 UTCVendor advisory
  18. 2026-06-28 22:15 UTCVendor advisory
  19. 2026-06-28 18:26 UTCVendor advisory
  20. 2026-06-28 14:37 UTCVendor advisory
  21. 2026-06-28 14:07 UTCEPSS rescore
  22. 2026-06-28 10:43 UTCVendor advisory
  23. 2026-06-28 06:54 UTCVendor advisory
  24. 2026-06-28 04:56 UTCEPSS rescore
  25. 2026-06-28 04:56 UTCEPSS rescore
  26. 2026-06-28 03:06 UTCVendor advisory
  27. 2026-06-27 23:18 UTCVendor advisory
  28. 2026-06-27 19:30 UTCVendor advisory
  29. 2026-06-27 15:40 UTCVendor advisory
  30. 2026-06-27 11:50 UTCVendor advisory
  31. 2026-06-27 08:01 UTCVendor advisory
  32. 2026-06-27 04:12 UTCVendor advisory
  33. 2026-06-27 03:08 UTCEPSS rescore
  34. 2026-06-27 00:03 UTCVendor advisory
  35. 2026-06-26 20:00 UTCVendor advisory
  36. 2026-06-26 16:12 UTCVendor advisory
  37. 2026-06-26 02:24 UTCVendor advisory
  38. 2026-06-25 22:36 UTCVendor advisory
  39. 2026-06-25 18:37 UTCVendor advisory
  40. 2026-06-25 13:49 UTCEPSS rescore
  41. 2026-06-24 14:05 UTCEPSS rescore
  42. 2026-06-23 21:33 UTCEPSS rescore
  43. 2026-06-23 21:33 UTCEPSS rescore
  44. 2026-06-22 14:25 UTCEPSS rescore
  45. 2026-06-22 14:25 UTCEPSS rescore
  46. 2026-06-21 14:56 UTCEPSS rescore
  47. 2026-06-21 14:56 UTCEPSS rescore
  48. 2026-06-21 01:59 UTCEPSS rescore
  49. 2026-06-19 19:25 UTCEPSS rescore
  50. 2026-06-18 17:52 UTCEPSS rescore
  51. 2026-06-18 17:52 UTCEPSS rescore
  52. 2026-06-17 17:53 UTCEPSS rescore
  53. 2026-06-16 17:52 UTCEPSS rescore
  54. 2026-06-15 17:49 UTCEPSS rescore
  55. 2026-06-13 23:00 UTCEPSS rescore
  56. 2026-06-12 23:12 UTCEPSS rescore
  57. 2026-06-12 23:12 UTCEPSS rescore
  58. 2026-06-11 14:00 UTCEPSS rescore
  59. 2026-06-10 22:18 UTCEPSS rescore
  60. 2026-06-10 13:22 UTCEPSS rescore
  61. 2026-06-10 13:22 UTCEPSS rescore
  62. 2026-06-08 14:17 UTCEPSS rescore
  63. 2026-06-08 14:17 UTCEPSS rescore
  64. 2026-06-07 15:25 UTCEPSS rescore
  65. 2026-06-07 15:25 UTCEPSS rescore
  66. 2026-06-06 13:47 UTCEPSS rescore
  67. 2026-06-06 13:47 UTCEPSS rescore
  68. 2026-06-05 22:47 UTCEPSS rescore
  69. 2026-06-05 06:10 UTCEPSS rescore
  70. 2026-06-05 06:10 UTCEPSS rescore
  71. 2026-06-04 13:12 UTCEPSS rescore
  72. 2026-06-04 13:12 UTCEPSS rescore
  73. 2026-06-02 20:13 UTCEPSS rescore
  74. 2026-06-01 13:52 UTCEPSS rescore
  75. 2026-06-01 13:52 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-45372?
CVE-2026-45372 is a critical vulnerability published on May 29, 2026. cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (isfieldvalue) is run before decoding, so…
When was CVE-2026-45372 disclosed?
CVE-2026-45372 was first published in the National Vulnerability Database on May 29, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45372 actively exploited?
CVE-2026-45372 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45372?
CVE-2026-45372 has a CVSS v3 base score of 9.9 (NVD).
How do I remediate CVE-2026-45372?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45372, 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.

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