CVE-2026-66338

HIGHNVD 7.27.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.2 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 91% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
7.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.2Exploit: None knownExposed: 0

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

A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests.

CVSS v3
7.2
EG Score
7.2(medium)
EG Risk
32(Track)
EG Risk 32/100SSVC: 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
Severity72% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

July 24, 2026

Last Modified

August 24, 2026

Advisory Details (2)

Auto-updated Jul 25, 2026
Patch available. Sources: redhat.
redhat

2506950 – (CVE-2026-66338) CVE-2026-66338 libsoup: libsoup: HTTP Request Smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()

https://bugzilla.redhat.com/show_bug.cgi?id=2506950
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-66338

Vendor Advisories for CVE-2026-66338(1)

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

Affected Packages

(6 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
libsoup2.42.74.3-1 ... 2.74.3-9 (16 versions)——
libsoup33.2.2-2 ... 3.6.6-1 (35 versions)——
Debian:13(2)
PackageVulnerable rangeFixed inDependents
libsoup2.42.74.3-10.1, 2.74.3-11——
libsoup33.6.5-3 ... 3.6.6-1 (8 versions)——
Debian:11(1)
PackageVulnerable rangeFixed inDependents
libsoup2.42.72.0-2 ... 2.74.3-9 (28 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libsoup33.6.5-3 ... 3.6.6-1 (8 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× 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 149 total refreshes for this CVE.

  1. 2026-09-15 09:34 UTCEG score recompute
  2. 2026-09-15 09:34 UTCGHSA enrichment
  3. 2026-09-14 11:19 UTCGHSA enrichment
  4. 2026-09-14 00:13 UTCEG score recompute
  5. 2026-09-14 00:13 UTCGHSA enrichment
  6. 2026-09-13 13:06 UTCGHSA enrichment
  7. 2026-09-13 01:59 UTCEG score recompute
  8. 2026-09-13 01:59 UTCGHSA enrichment
  9. 2026-09-12 14:47 UTCGHSA enrichment
  10. 2026-09-12 03:41 UTCGHSA enrichment
  11. 2026-09-11 16:35 UTCEG score recompute
  12. 2026-09-11 16:35 UTCGHSA enrichment
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 09:37 UTCEPSS rescore
  15. 2026-09-11 02:29 UTCGHSA enrichment
  16. 2026-09-10 13:33 UTCEG score recompute
  17. 2026-09-10 13:33 UTCGHSA enrichment
  18. 2026-09-09 08:42 UTCEG score recompute
  19. 2026-09-09 08:42 UTCGHSA enrichment
  20. 2026-09-08 22:01 UTCEPSS rescore
  21. 2026-09-07 21:23 UTCEG score recompute
  22. 2026-09-07 21:23 UTCGHSA enrichment
  23. 2026-09-07 16:01 UTCEPSS rescore
  24. 2026-09-06 19:14 UTCEG score recompute
  25. 2026-09-06 19:14 UTCGHSA enrichment
Show 75 more
  1. 2026-09-06 13:47 UTCEPSS rescore
  2. 2026-09-06 08:07 UTCGHSA enrichment
  3. 2026-09-05 19:22 UTCEG score recompute
  4. 2026-09-05 19:22 UTCGHSA enrichment
  5. 2026-09-05 15:31 UTCEPSS rescore
  6. 2026-09-05 06:52 UTCEG score recompute
  7. 2026-09-05 06:52 UTCGHSA enrichment
  8. 2026-09-04 12:44 UTCEG score recompute
  9. 2026-09-04 12:43 UTCGHSA enrichment
  10. 2026-09-04 05:07 UTCEPSS rescore
  11. 2026-09-02 14:12 UTCEPSS rescore
  12. 2026-09-01 23:15 UTCEG score recompute
  13. 2026-09-01 23:15 UTCGHSA enrichment
  14. 2026-09-01 13:54 UTCEPSS rescore
  15. 2026-08-30 22:26 UTCEG score recompute
  16. 2026-08-30 22:26 UTCGHSA enrichment
  17. 2026-08-30 19:17 UTCEPSS rescore
  18. 2026-08-30 11:20 UTCEG score recompute
  19. 2026-08-30 11:20 UTCGHSA enrichment
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-30 00:14 UTCEG score recompute
  22. 2026-08-30 00:14 UTCGHSA enrichment
  23. 2026-08-28 21:42 UTCEPSS rescore
  24. 2026-08-27 22:58 UTCGHSA enrichment
  25. 2026-08-27 11:51 UTCGHSA enrichment
  26. 2026-08-27 00:45 UTCEG score recompute
  27. 2026-08-27 00:45 UTCGHSA enrichment
  28. 2026-08-26 14:47 UTCEPSS rescore
  29. 2026-08-26 13:39 UTCGHSA enrichment
  30. 2026-08-26 02:24 UTCGHSA enrichment
  31. 2026-08-25 15:18 UTCEG score recompute
  32. 2026-08-25 15:18 UTCGHSA enrichment
  33. 2026-08-25 13:49 UTCEPSS rescore
  34. 2026-08-25 04:06 UTCGHSA enrichment
  35. 2026-08-24 17:01 UTCEG score recompute▲ 1.80
  36. 2026-08-24 17:00 UTCGHSA enrichment
  37. 2026-08-24 16:57 UTCNVD updateCVSS v3 → 7.2 · severity → HIGH
  38. 2026-08-23 19:27 UTCEG score recompute
  39. 2026-08-23 19:27 UTCGHSA enrichment
  40. 2026-08-23 00:19 UTCEPSS rescore
  41. 2026-08-22 19:40 UTCEG score recompute
  42. 2026-08-22 19:40 UTCGHSA enrichment
  43. 2026-08-21 23:49 UTCEPSS rescore
  44. 2026-08-21 19:52 UTCEG score recompute
  45. 2026-08-21 19:52 UTCGHSA enrichment
  46. 2026-08-20 22:56 UTCEPSS rescore
  47. 2026-08-20 20:04 UTCGHSA enrichment
  48. 2026-08-19 20:16 UTCEG score recompute
  49. 2026-08-19 20:16 UTCGHSA enrichment
  50. 2026-08-19 17:04 UTCEPSS rescore
  51. 2026-08-18 18:51 UTCGHSA enrichment
  52. 2026-08-17 17:11 UTCEG score recompute
  53. 2026-08-17 17:11 UTCGHSA enrichment
  54. 2026-08-17 13:47 UTCEPSS rescore
  55. 2026-08-16 17:23 UTCEG score recompute
  56. 2026-08-16 17:23 UTCGHSA enrichment
  57. 2026-08-16 14:56 UTCEPSS rescore
  58. 2026-08-15 17:35 UTCEG score recompute
  59. 2026-08-15 17:35 UTCGHSA enrichment
  60. 2026-08-15 01:30 UTCEPSS rescore
  61. 2026-08-14 17:46 UTCEG score recompute
  62. 2026-08-14 17:46 UTCGHSA enrichment
  63. 2026-08-13 22:00 UTCEPSS rescore
  64. 2026-08-13 17:55 UTCGHSA enrichment
  65. 2026-08-12 18:07 UTCEG score recompute
  66. 2026-08-12 18:07 UTCGHSA enrichment
  67. 2026-08-12 13:51 UTCEPSS rescore
  68. 2026-08-11 18:19 UTCEG score recompute
  69. 2026-08-11 18:19 UTCGHSA enrichment
  70. 2026-08-11 00:00 UTCEPSS rescore
  71. 2026-08-10 18:27 UTCGHSA enrichment
  72. 2026-08-09 18:37 UTCEG score recompute
  73. 2026-08-09 18:37 UTCGHSA enrichment
  74. 2026-08-09 13:47 UTCEPSS rescore
  75. 2026-08-08 18:50 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-66338?
CVE-2026-66338 is a high vulnerability published on July 24, 2026. A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend…
When was CVE-2026-66338 disclosed?
CVE-2026-66338 was first published in the National Vulnerability Database on July 24, 2026, with the most recent update on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66338 actively exploited?
CVE-2026-66338 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 91.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66338?
CVE-2026-66338 has a CVSS v3 base score of 7.2 (NVD).
How do I remediate CVE-2026-66338?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66338, 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

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