CVE catalog
CVE-2026-1525
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with
- Severity
- Critical · CVSS 9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.51% · Oct 25, 2026
Undici allows duplicate HTTP Content-Length headers when they are provided in an array with case-variant names (e.g., Content-Length and content-length). This produces malformed HTTP/1.1 requests with multiple conflicting Content-Length values on the wire. Who is impacted: * Applications using undici.request(), undici.Client, or similar low-level APIs with headers passed as flat arrays * Applications that accept user-controlled header names without case-normalization Potential consequences: * Denial of Service: Strict HTTP parsers (proxies, servers) will reject requests with duplicate Content-Length headers (400 Bad Request) * HTTP Request Smuggling: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | node-undici | sid | 8.12.2+dfsg+~cs3.2.3-2 | fixed |
| Debian | node-undici | forky | 8.10.2+dfsg+~cs3.2.2-1 | fixed |
| Debian | node-undici | trixie | 7.3.0+dfsg1+~cs24.12.11-1 | vulnerable |
| Debian | node-undici | bookworm | 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4 | not affected |
| Debian | node-undici | bookworm-security | 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3 | not affected |
| Npm | undici | Not reported | 6.24.0 | fixed |
| Npm | undici | Not reported | 7.24.0 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | node-undici | source | sid | 7.24.5+dfsg+~cs3.2.0-1 | not yet assigned | Not reported | [1130879] |
| Debian | node-undici | source | forky | 7.24.5+dfsg+~cs3.2.0-1 | not yet assigned | Not reported | [1130879] |
| Debian | node-undici | source | trixie | (unfixed) | not yet assigned | Not reported | [1130879] |
| Debian | node-undici | source | bookworm | Not affected | unimportant | Not reported | [1130879] |
| Npm | undici | npm | Not reported | 6.24.0 | Not reported | Not reported | Not reported |
| Npm | undici | npm | Not reported | 7.24.0 | Not reported | Not reported | Not reported |
Notes
[trixie] node-undici: Minor issue
OpenFactory catalog packages
[Debian 13 (Trixie)]
- [libllhttp9.2]Affected
Source package: [node-undici]
Details (2)
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· amd64 · trixieAffected
nvd · node-undici · debian · 13
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· arm64 · trixieAffected
nvd · node-undici · debian · 13
- [libllhttp-dev]Affected
Source package: [node-undici]
Details (2)
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· amd64 · trixieAffected
nvd · node-undici · debian · 13
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· arm64 · trixieAffected
nvd · node-undici · debian · 13
- [node-llhttp]Affected
Source package: [node-undici]
Details (2)
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· all · trixieAffected
nvd · node-undici · debian · 13
9.2.1~7.3.0+dfsg1+~cs24.12.11-1· all · trixieAffected
nvd · node-undici · debian · 13
- [node-undici]Affected
Details (2)
7.3.0+dfsg1+~cs24.12.11-1· all · trixieAffected
nvd · node-undici · debian · 13
7.3.0+dfsg1+~cs24.12.11-1· all · trixieAffected
nvd · node-undici · debian · 13
[Debian 12 (Bookworm)]
- [node-llhttp]Not affected
Source package: [node-undici]
Details (4)
8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4· all · bookwormNot affected
nvd · node-undici · debian · bookworm
8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4· all · bookwormNot affected
nvd · node-undici · debian · bookworm
8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3· all · bookworm-securityNot affected
nvd · node-undici · debian · bookworm
8.1.0~5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3· all · bookworm-securityNot affected
nvd · node-undici · debian · bookworm
- [node-undici]Not affected
Details (4)
5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4· all · bookwormNot affected
nvd · node-undici · debian · bookworm
5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4· all · bookwormNot affected
nvd · node-undici · debian · bookworm
5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3· all · bookworm-securityNot affected
nvd · node-undici · debian · bookworm
5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3· all · bookworm-securityNot affected
nvd · node-undici · debian · bookworm
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/rhsa-2026_7080.json]
- [https://github.com/advisories/GHSA-2mjp-6q6p-2qxm]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-1525]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-1525]
- [https://security-tracker.debian.org/tracker/CVE-2026-1525]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-1525.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0933.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]