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CVE-2026-1527

undici is vulnerable to CRLF Injection via upgrade option

Published: Mar 12, 2026Updated: Mar 20, 2026 Sources: CVE List NVD GHSACWE-93
NVD MITRE
4.6CVSSMEDIUM
EPSS Score
0.3%
Top 83.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to: * Inject arbitrary HTTP headers * Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch) The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters: // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` }

CVSS Vector Breakdown

AV:NAC:LPR:LUI:RS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-93

Affected Products

undicinodejsOSS Libraries
undicinpmOSS Libraries
undiciundici
On-prem
OSS Libraries / npm
nodejsoss-projectUSOSS Librariesaka node.js, node
npmpackage-ecosystemOSS Libraries
undicioss-projectOSS Librariesaka undici

Exploitability

Official Patch Available
Workaround Available

References

https://cna.openjsf.org/security-advisories.html
cna.openjsf.org
https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq
github.com
https://hackerone.com/reports/3487198
hackerone.com
and 2 more references View all →

Timeline

Published
Mar 12, 2026
Last Updated
Mar 20, 2026

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