uhttpd vulnerable to HTTP request smuggling via invalid chunk-length state reset
CVSS score
3.7
EPSS probability
—
Risk score
0.4
Published
2 h ago
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Vulnerability description
DayBreach AI Explanation
Verified against sourcesSources read
2
Source agreement
Tam uyum
Evidence confidence
%63
Short explanation
uhttpd is a small HTTP server. In unpatched repository snapshots, `client_poll_post_data()` in `client.c` consumes an invalid chunk-length line exceeding INT_MAX and clears state variables without draining the body, causing HTTP request smuggling and request-boundary desynchronization.
This vulnerability allows attackers to manipulate request boundaries and trigger HTTP request smuggling by having controller-aligned body bytes parsed as a separate request on the same connection.
What should be done?
- Apply the vendor advisory guidance
- Reference commit b78f518478794e16ba3568fc1258e40bf3e8eb3b
- Reference commit 34460b8211d676ef1b9f40d6b775c5e112933690
Chain of evidence and sources
uhttpd içindeki client_poll_post_data() fonksiyonu geçersiz parça uzunluğu satırını işler ve durumu sıfırlar.
Saldırgan denetimindeki gövde baytları aynı bağlantı üzerinde ayrı bir istek olarak işlenir ve HTTP istek kaçakçılığına yol açar.
Show the technical text from the sources
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.
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE: CWE-444
This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-55612 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | openwrt | uhttpd | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 3.7 | CVSS V3_1 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | CVE CNA |
| 3.7 | CVSS V31 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-55612 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-55612 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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