CVE-2026-3256

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-28. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

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

HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids.

HTTP::Session defaults to using HTTP::Session::ID::SHA1 to generate session ids using a SHA-1 hash seeded with the built-in rand function, the high resolution epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage.

The distribution includes HTTP::session::ID::MD5 which contains a similar flaw, but uses the MD5 hash instead.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
42%
KEV
Not listed

Published

March 28, 2026

Last Modified

June 29, 2026

Advisory Details (5)

Auto-updated Aug 22, 2026
No patch confirmed yet.
generic

oss-security - CVE-2026-3256: HTTP::Session versions through 0.53 for Perl defaults to using insecurely generated session ids

http://www.openwall.com/lists/oss-security/2026/03/28/5
generic

CPAN Author’s Guide to Random Data for Security — CPAN Security Group (CPANSec) 🦆

https://security.metacpan.org/docs/guides/random-data-for-security.html
generic

Client Challenge

https://metacpan.org/release/TOKUHIROM/http-session-0.54/changes
generic

Client Challenge

https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/SHA1.pm
generic

Client Challenge

https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/MD5.pm

Vendor Advisories for CVE-2026-3256(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 75× 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 114 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-3256?
CVE-2026-3256 is a critical vulnerability published on March 28, 2026. HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids. HTTP::Session defaults to using HTTP::Session::ID::SHA1 to generate session ids using a SHA-1 hash seeded with the built-in rand function, the high resolution epoch time, and the PID. The PID will come…
When was CVE-2026-3256 disclosed?
CVE-2026-3256 was first published in the National Vulnerability Database on March 28, 2026, with the most recent update on June 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3256 actively exploited?
CVE-2026-3256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 57.5% of all scored CVEs.
What is the CVSS score of CVE-2026-3256?
CVE-2026-3256 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-3256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3256, 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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