CVE catalog
CVE-2026-9679
Impact: undici's cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 §5
- Severity
- Medium · CVSS 5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.26% · Oct 25, 2026
Impact: undici's cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 §5.4 does not specify any decoding and browsers do not decode either. Applications that parse a Set-Cookie header and then forward the parsed value into a response header (proxies, middleware, SSR frameworks) become vulnerable to HTTP response header injection: an attacker-controlled upstream can inject arbitrary Set-Cookie, Location, or Cache-Control headers into the application's downstream response, enabling session fixation, open redirect, or cache poisoning. Affected applications are those that use undici's cookie parsing (parseSetCookie, parseCookie, getSetCookies) and forward the parsed cookie value into a response header. This was introduced in undici 7.0.0 via PR #3789. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: If upgrade is not immediately possible, do not forward values returned by parseSetCookie/parseCookie/getSetCookies directly into response headers; sanitize the value first to strip or reject CR, LF, NUL, ;, and = bytes.
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 |
| Cpe | undici | Not reported | 6.27.0 | fixed |
| Cpe | undici | Not reported | 7.28.0 | fixed |
| Cpe | undici | Not reported | 8.5.0 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | node-undici | source | sid | 8.5.0+dfsg+~cs3.2.0-1 | not yet assigned | Not reported | [1140363] |
| Debian | node-undici | source | forky | 8.5.0+dfsg+~cs3.2.0-1 | not yet assigned | Not reported | [1140363] |
| Debian | node-undici | source | trixie | (unfixed) | not yet assigned | Not reported | [1140363] |
| Debian | node-undici | source | bookworm | Not affected | unimportant | Not reported | [1140363] |
| Cpe | undici | cpe | Not reported | 6.27.0 | Not reported | Not reported | Not reported |
| Cpe | undici | cpe | Not reported | 7.28.0 | Not reported | Not reported | Not reported |
| Cpe | undici | cpe | Not reported | 8.5.0 | 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/suse-su-2026_22565-1.json]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-9679]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-9679]
- [https://security-tracker.debian.org/tracker/CVE-2026-9679]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9679.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-2618.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]