CVE-2026-6276

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-05-13. NVD baseline CVSS 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 0

A fix is available — apply it.

Using libcurl, when a custom Host: header is first set for an HTTP request and a second request is subsequently done using the same *easy handle* but without the custom Host: header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

May 13, 2026

Last Modified

September 15, 2026

Advisory Details (4)

Auto-updated May 13, 2026
No patch confirmed yet.
generic

HackerOne

https://hackerone.com/reports/3671818
generic

oss-security - [ADVISORY] curl: CVE-2026-6276: stale custom cookie host causes cookie leak

http://www.openwall.com/lists/oss-security/2026/04/29/13
generic
https://curl.se/docs/CVE-2026-6276.json
generic

curl - stale custom cookie host causes cookie leak - CVE-2026-6276

https://curl.se/docs/CVE-2026-6276.html

Vendor Advisories for CVE-2026-6276(3)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibcurl4t64 (8.18.0-1ubuntu2.1) @ resolute2026-09-15ubuntu
redhatcurl-main-8.20.0-0.1.hum12026-05-02redhat

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

(6 across 6 ecosystems)
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
curl—8.20.0-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
curl—8.20.0-r0—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
curl7.74.0-1.3 ... 8.9.1-2~bpo12+1 (219 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
curl7.88.1-10 ... 8.9.1-2~bpo12+1 (178 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
curl8.14.1-2, 8.14.1-2+deb13u1, 8.14.1-2+deb13u2, 8.14.1-2+deb13u2~bpo13+1, 8.14.1-2+deb13u38.14.1-2+deb13u4—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
curl8.14.1-2 ... 8.20.0~rc2-1+exp1 (47 versions)8.20.0~rc3-1—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 34× 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 288 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-6276?
CVE-2026-6276 is a high vulnerability published on May 13, 2026. Using libcurl, when a custom Host: header is first set for an HTTP request and a second request is subsequently done using the same easy handle but without the custom Host: header set, the second request would use stale information and pass on cookies meant for the first host in the second request.…
When was CVE-2026-6276 disclosed?
CVE-2026-6276 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on September 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6276 actively exploited?
CVE-2026-6276 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 77.7% of all scored CVEs.
What is the CVSS score of CVE-2026-6276?
CVE-2026-6276 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-6276?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6276, 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-2026-6276

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