Vulnerability · Published Oct 30, 2026 · Assigned by GitHub_M

CVE-2026-55612uhttpd vulnerable to HTTP request smuggling via invalid chunk-length state reset

Low 3.7

In plain English

A low-severity security flaw in uhttpd from openwrt. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 3.1)3.7Low

Exploit odds (30 days)0.3%top 78.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

uhttpd is a small HTTP server. In unpatched repository snapshots, `client_poll_post_data()` in `client.c` consumes an invalid chunk-length line, such as a size exceeding INT_MAX, then clears `r->content_length` and `r->transfer_chunked` without draining the remaining body or setting `request.connection_close`. The completion check treats the chunked POST as finished and the keep-alive parser returns to `CLIENT_STATE_INIT`. Attacker-controlled body bytes aligned as a complete HTTP request are then parsed and processed as another request on the same connection, causing HTTP request smuggling and request-boundary desynchronization. Commits b78f518478794e16ba3568fc1258e40bf3e8eb3b and 34460b8211d676ef1b9f40d6b775c5e112933690 patch the issue.

Affected products (as reported)

Vendor	Product	Versions
openwrt	uhttpd	>= b7c85a2819b3869279a669d5681f574824589c6c, < b78f518478794e16ba3568fc1258e40bf3e8eb3b>= b7c85a2819b3869279a669d5681f574824589c6c, < 34460b8211d676ef1b9f40d6b775c5e112933690

Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

References

https://github.com/openwrt/uhttpd/security/advisories/GHSA-p55c-rmhc-qfm5 x_refsource_CONFIRM
https://github.com/openwrt/uhttpd/commit/34460b8211d676ef1b9f40d6b775c5e112933690 x_refsource_MISC
https://github.com/openwrt/uhttpd/commit/b78f518478794e16ba3568fc1258e40bf3e8eb3b x_refsource_MISC