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 78% 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
Trending — 4 sources updated this weekElevated
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.9Exploit: Elevated riskExposed: 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
76(Attend)
EG Risk 76/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity99% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

May 29, 2026

Last Modified

July 22, 2026

Advisory Details (1)

Auto-updated Sep 16, 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-httplib0.14t64 (0.14.3+ds-1.1ubuntu0.1~esm2) @ noble2026-09-14ubuntu

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.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
cpp-httplib0.11.4+ds-1 ... 0.41.0+ds-3~bpo13+1 (27 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
cpp-httplib0.18.7-1 ... 0.41.0+ds-3~bpo13+1 (9 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
cpp-httplib0.18.7-1 ... 0.41.0+ds-3~bpo13+1 (8 versions)——

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 9× in last 7d / 47× 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 272 total refreshes for this CVE.

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

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 0% probability of exploitation in the next 30 days, which ranks it in the top 78.0% of all scored CVEs.
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.

Dependency Blast Radius

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