cpp-httplib is a C++ header-only HTTP/HTTPS library. In version 0.49.0, the chunked-response trailer output path writes trailer header names and values directly to the socket without validating them, allowing CRLF sequences in a trailer field to inject additional headers or split the HTTP response. Unlike every other header-writing path in the library, the trailer-writing code applies none of the field-name and field-value checks that reject carriage return and line feed, so an application that places attacker-influenced data into a chunked response trailer emits attacker-controlled CRLF onto the wire. This enables HTTP response splitting, letting an attacker forge response headers or inject a second response. This issue is fixed in version 0.50.0.
CVE-2026-77341
This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 81% 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).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.3
- EG Score
- 5.3(medium)
- EG Risk
- 40(Track)EG Risk 40/100SSVC: Track
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 computedSeverity53% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 19%
- KEV
- Not listed
Published
August 27, 2026
Last Modified
August 28, 2026
Advisory Details (2)
Auto-updated Aug 27, 2026commit 568d434e72fc (yhirose/cpp-httplib)
Patch available: yhirose/cpp-httplib v0.50.0 (contains commit 568d434e72fc)
https://github.com/yhirose/cpp-httplib/commit/568d434e72fc51729d0ad33abffb181e5f7a453dCRLF injection via unvalidated HTTP trailer headers in chunked response writing · Advisory · yhirose/cpp-httplib · GitHub
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-2r2h-jc8w-w66cWeakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 8× 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.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-29 21:24 UTCEG score recompute
- 2026-08-28 21:42 UTCEPSS rescore
- 2026-08-28 20:40 UTCEG score recompute
- 2026-08-28 19:46 UTCEG score recompute
- 2026-08-28 00:30 UTCEG score recompute
- 2026-08-27 23:23 UTCEG score recompute
- 2026-08-27 23:22 UTCMITRE cvelistV5first tracked
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-77341
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