CVE-2026-9679

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 83% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
31(Track)
EG Risk 31/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
KEV
Not listed

Published

June 17, 2026

Last Modified

June 25, 2026

Advisory Details (2)

Auto-updated Jun 17, 2026
Patch available. Sources: github.
github Patch Available

undici vulnerable to HTTP header injection via Set-Cookie percent-decoding · Advisory · nodejs/undici · GitHub

https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv
generic

Security Advisories | OpenJS Foundation CVE Numbering Authority

https://cna.openjsf.org/security-advisories.html

Vendor Advisories for CVE-2026-9679(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatodf4/rook-ceph-rhel9-operator:17867068802026-08-18redhat
redhatnodejs24-main-24.18.0-0.3.hum12026-07-11redhat
redhatnodejs26-main-26.5.0-1.3.hum12026-07-10redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 3 ecosystems)
Debian:13(1)
PackageVulnerable rangeFixed inDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 8.9.0+dfsg+~cs3.2.0-1 (15 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 7.3.0+dfsg1+~cs24.12.11-2 (11 versions)8.5.0+dfsg+~cs3.2.0-1—
npm(1)
PackageVulnerable rangeFixed inDependents
undici—8.5.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 79× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 128 total refreshes for this CVE.

  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-25 04:30 UTCEG score recompute
  3. 2026-08-25 04:30 UTCVendor advisory
  4. 2026-08-24 14:18 UTCEPSS rescore
  5. 2026-08-24 05:19 UTCVendor advisory
  6. 2026-08-23 04:12 UTCEG score recompute
  7. 2026-08-23 04:12 UTCVendor advisory
  8. 2026-08-23 00:19 UTCEPSS rescore
  9. 2026-08-21 23:49 UTCEPSS rescore
  10. 2026-08-21 07:24 UTCEG score recompute
  11. 2026-08-21 07:24 UTCVendor advisory
  12. 2026-08-20 22:56 UTCEPSS rescore
  13. 2026-08-20 08:13 UTCEG score recompute
  14. 2026-08-20 08:13 UTCVendor advisory
  15. 2026-08-19 17:04 UTCEPSS rescore
  16. 2026-08-19 08:09 UTCEG score recompute
  17. 2026-08-19 08:09 UTCVendor advisory
  18. 2026-08-18 13:49 UTCEPSS rescore
  19. 2026-08-17 13:47 UTCEPSS rescore
  20. 2026-08-16 17:09 UTCEG score recompute
  21. 2026-08-16 17:09 UTCVendor advisory
  22. 2026-08-16 14:56 UTCEPSS rescore
  23. 2026-08-16 02:15 UTCEPSS rescore
  24. 2026-08-15 17:58 UTCEG score recompute
  25. 2026-08-15 17:58 UTCVendor advisory
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  1. 2026-08-15 01:31 UTCEPSS rescore
  2. 2026-08-14 18:46 UTCEG score recompute
  3. 2026-08-14 18:46 UTCVendor advisory
  4. 2026-08-13 22:00 UTCEPSS rescore
  5. 2026-08-13 19:35 UTCVendor advisory
  6. 2026-08-12 20:24 UTCEG score recompute
  7. 2026-08-12 20:24 UTCVendor advisory
  8. 2026-08-12 13:51 UTCEPSS rescore
  9. 2026-08-11 21:13 UTCEG score recompute
  10. 2026-08-11 21:13 UTCVendor advisory
  11. 2026-08-11 13:43 UTCEPSS rescore
  12. 2026-08-11 00:00 UTCEPSS rescore
  13. 2026-08-10 22:02 UTCVendor advisory
  14. 2026-08-09 22:51 UTCEG score recompute
  15. 2026-08-09 22:51 UTCVendor advisory
  16. 2026-08-09 13:47 UTCEPSS rescore
  17. 2026-08-08 23:40 UTCEG score recompute
  18. 2026-08-08 23:40 UTCVendor advisory
  19. 2026-08-08 16:37 UTCEPSS rescore
  20. 2026-08-08 00:29 UTCEG score recompute
  21. 2026-08-08 00:29 UTCVendor advisory
  22. 2026-08-07 16:30 UTCEPSS rescore
  23. 2026-08-07 01:18 UTCEG score recompute
  24. 2026-08-07 01:18 UTCVendor advisory
  25. 2026-08-06 13:47 UTCEPSS rescore
  26. 2026-08-06 02:07 UTCEG score recompute
  27. 2026-08-06 02:07 UTCVendor advisory
  28. 2026-08-05 19:17 UTCEPSS rescore
  29. 2026-08-05 02:56 UTCEG score recompute
  30. 2026-08-05 02:56 UTCVendor advisory
  31. 2026-08-04 15:10 UTCEPSS rescore
  32. 2026-08-04 10:39 UTCEPSS rescore
  33. 2026-08-04 02:53 UTCEG score recompute
  34. 2026-08-04 02:53 UTCVendor advisory
  35. 2026-08-03 10:36 UTCEPSS rescore
  36. 2026-08-03 03:42 UTCVendor advisory
  37. 2026-08-02 04:31 UTCEG score recompute
  38. 2026-08-02 04:31 UTCVendor advisory
  39. 2026-08-02 02:27 UTCEPSS rescore
  40. 2026-08-01 05:20 UTCEG score recompute
  41. 2026-08-01 05:20 UTCVendor advisory
  42. 2026-08-01 04:16 UTCEPSS rescore
  43. 2026-07-31 03:55 UTCEG score recompute
  44. 2026-07-31 03:55 UTCVendor advisory
  45. 2026-07-30 16:28 UTCEPSS rescore
  46. 2026-07-30 03:34 UTCEG score recompute
  47. 2026-07-30 03:34 UTCVendor advisory
  48. 2026-07-30 01:30 UTCEPSS rescore
  49. 2026-07-29 02:07 UTCEG score recompute
  50. 2026-07-29 02:07 UTCVendor advisory
  51. 2026-07-28 15:37 UTCEPSS rescore
  52. 2026-07-27 18:15 UTCEG score recompute
  53. 2026-07-27 18:15 UTCVendor advisory
  54. 2026-07-27 14:14 UTCEPSS rescore
  55. 2026-07-26 19:04 UTCEG score recompute
  56. 2026-07-26 19:04 UTCVendor advisory
  57. 2026-07-26 14:54 UTCEPSS rescore
  58. 2026-07-25 14:18 UTCEPSS rescore
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  60. 2026-07-23 14:18 UTCEPSS rescore
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  63. 2026-07-21 15:25 UTCEPSS rescore
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  65. 2026-07-20 17:08 UTCEPSS rescore
  66. 2026-07-19 14:31 UTCEPSS rescore
  67. 2026-07-19 02:29 UTCEPSS rescore
  68. 2026-07-18 10:04 UTCEPSS rescore
  69. 2026-07-16 22:36 UTCVendor advisory
  70. 2026-07-16 17:03 UTCEPSS rescore
  71. 2026-07-15 23:25 UTCVendor advisory
  72. 2026-07-15 16:57 UTCEPSS rescore
  73. 2026-07-15 02:00 UTCEPSS rescore
  74. 2026-07-15 00:14 UTCVendor advisory
  75. 2026-07-14 00:52 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-9679?
CVE-2026-9679 is a medium vulnerability published on June 17, 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…
When was CVE-2026-9679 disclosed?
CVE-2026-9679 was first published in the National Vulnerability Database on June 17, 2026, with the most recent update on June 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-9679 actively exploited?
CVE-2026-9679 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 83.0% of all scored CVEs.
What is the CVSS score of CVE-2026-9679?
CVE-2026-9679 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-9679?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-9679, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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