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CVE-2026-77341

MEDIUMCVSS 5.3/10EPSS 0.27%

Last modified

CVE-2026-77341 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 4.0
5.3/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.27%

19.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
yhirosecpp-httplib>= 0.49.0, < 0.50.0

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-77341?
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.
How severe is CVE-2026-77341?
CVE-2026-77341 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.
How do I fix CVE-2026-77341?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST