CVE-2026-66357

HIGHPre-NVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 74% 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
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved.

This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.

CVSS v3
8.3
EG Score
8.3(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: 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
Severity83% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 8, 2026

Advisory Details (6)

Auto-updated Sep 1, 2026
Patch available. Sources: github_commit, github.
github_commit

commit e640d599287d (erlang/otp)

Fix landed in erlang/otp commit e640d599287d — awaiting tagged release

https://github.com/erlang/otp/commit/e640d599287d2eba919e6f13b91f042d7dbe6ff4
github_commit

commit 273d8958de38 (erlang/otp)

Fix landed in erlang/otp commit 273d8958de38 — awaiting tagged release

https://github.com/erlang/otp/commit/273d8958de38ff2a7fe0c5dcc5b6bfe6f65717f3
github_commit

commit 220d618d2479 (erlang/otp)

Fix landed in erlang/otp commit 220d618d2479 — awaiting tagged release

https://github.com/erlang/otp/commit/220d618d2479a7180b4a06d0c5aacfaa4af4a85b
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-66357
generic

CVE-2026-66357

https://cna.erlef.org/cves/CVE-2026-66357.html
github Patch Available

HTTP Request Smuggling via obs-fold Header Continuation in httpd · Advisory · erlang/otp · GitHub

https://github.com/erlang/otp/security/advisories/GHSA-qh2f-33hj-37qf

Vendor Advisories for CVE-2026-66357(1)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
erlang1:25.2.3+dfsg-1 ... 1:29.0~rc3+dfsg-4 (79 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
erlang1:27.3.4.1+dfsg-1 ... 1:29.0~rc3+dfsg-4 (40 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
erlang1:27.3.4.1+dfsg-1 ... 1:29.0~rc3+dfsg-4 (37 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 23× in last 7d / 63× 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.

  1. 2026-09-19 18:36 UTCEG score recompute
  2. 2026-09-19 18:36 UTCVendor advisory
  3. 2026-09-19 05:40 UTCEG score recompute
  4. 2026-09-19 05:40 UTCVendor advisory
  5. 2026-09-18 19:28 UTCEPSS rescore
  6. 2026-09-18 16:43 UTCVendor advisory
  7. 2026-09-18 03:46 UTCEG score recompute
  8. 2026-09-18 03:46 UTCVendor advisory
  9. 2026-09-17 14:49 UTCVendor advisory
  10. 2026-09-17 01:53 UTCEG score recompute
  11. 2026-09-17 01:53 UTCVendor advisory
  12. 2026-09-16 14:08 UTCEPSS rescore
  13. 2026-09-16 12:56 UTCEG score recompute
  14. 2026-09-16 12:56 UTCVendor advisory
  15. 2026-09-16 05:15 UTCEPSS rescore
  16. 2026-09-15 23:59 UTCVendor advisory
  17. 2026-09-15 11:03 UTCEG score recompute
  18. 2026-09-15 11:03 UTCVendor advisory
  19. 2026-09-14 21:53 UTCVendor advisory
  20. 2026-09-14 08:54 UTCVendor advisory
  21. 2026-09-13 19:58 UTCEG score recompute
  22. 2026-09-13 19:58 UTCVendor advisory
  23. 2026-09-13 07:01 UTCVendor advisory
  24. 2026-09-12 18:05 UTCEG score recompute
  25. 2026-09-12 18:05 UTCVendor advisory
Show 38 more
  1. 2026-09-12 05:05 UTCVendor advisory
  2. 2026-09-11 16:08 UTCEG score recompute
  3. 2026-09-11 16:08 UTCVendor advisory
  4. 2026-09-11 14:53 UTCEPSS rescore
  5. 2026-09-11 09:37 UTCEPSS rescore
  6. 2026-09-10 14:13 UTCEG score recompute
  7. 2026-09-09 12:19 UTCVendor advisory
  8. 2026-09-08 23:23 UTCEG score recompute
  9. 2026-09-08 23:23 UTCVendor advisory
  10. 2026-09-08 22:01 UTCEPSS rescore
  11. 2026-09-08 01:28 UTCEG score recompute
  12. 2026-09-08 01:28 UTCVendor advisory
  13. 2026-09-08 01:15 UTCEG score recompute
  14. 2026-09-08 01:15 UTCVendor advisory
  15. 2026-09-07 19:54 UTCEG score recompute
  16. 2026-09-07 19:54 UTCVendor advisory
  17. 2026-09-07 16:01 UTCEPSS rescore
  18. 2026-09-07 06:57 UTCVendor advisory
  19. 2026-09-06 17:59 UTCEG score recompute
  20. 2026-09-06 17:59 UTCVendor advisory
  21. 2026-09-06 13:47 UTCEPSS rescore
  22. 2026-09-06 05:02 UTCVendor advisory
  23. 2026-09-05 16:05 UTCEG score recompute
  24. 2026-09-05 16:05 UTCVendor advisory
  25. 2026-09-05 15:31 UTCEPSS rescore
  26. 2026-09-05 03:09 UTCVendor advisory
  27. 2026-09-04 14:10 UTCEG score recompute
  28. 2026-09-04 14:10 UTCVendor advisory
  29. 2026-09-04 05:07 UTCEPSS rescore
  30. 2026-09-04 01:14 UTCVendor advisory
  31. 2026-09-03 12:16 UTCVendor advisory
  32. 2026-09-02 23:16 UTCEG score recompute
  33. 2026-09-02 14:12 UTCEPSS rescore
  34. 2026-09-01 16:25 UTCEG score recompute
  35. 2026-09-01 16:10 UTCEG score recompute
  36. 2026-09-01 15:40 UTCEG score recompute
  37. 2026-09-01 14:44 UTCEG score recompute
  38. 2026-09-01 14:43 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-66357?
CVE-2026-66357 is a high vulnerability published on September 1, 2026. httpd has never implemented obs-fold (RFC 2616 §2.2 / RFC 7230 §3.2.4 header continuation lines). Every CRLF followed by a non-CRLF octet unconditionally starts a new header. This missing feature became a security concern as the understanding of HTTP request smuggling attacks evolved. This issue…
When was CVE-2026-66357 disclosed?
CVE-2026-66357 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66357 actively exploited?
CVE-2026-66357 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 73.9% of all scored CVEs.
What is the CVSS score of CVE-2026-66357?
CVE-2026-66357 has a CVSS v3 base score of 8.3 (NVD).
How do I remediate CVE-2026-66357?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66357, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-66357

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