CVE-2026-74766

HIGHPre-NVD 8.48.4—
EchelonGraph scoreHIGH confidence

Score 8.4 from GitHub Security Advisory (severity: HIGH) published 2026-09-22. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
8.4EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 8.4Exploit: None knownExposed services: Not assessed

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

Net::IDN::Punycode versions from 2.301 before 2.590 for Perl allow a heap use-after-free via a decoded code point that reallocates the output buffer in decode_punycode.

The XS backend inserts each decoded code point into the string buffer of the scalar it returns. decode_punycode computes the insertion pointer first and only then grows the buffer when the code point does not fit. The growth reallocates the buffer and updates every pointer except the insertion pointer, so the move that follows and the write of the code point go through a freed pointer. The buffer starts at twice the label length, and a code point above U+FFFF takes four bytes in the output, so a label of such code points outgrows it and forces the reallocation.

Version 2.301, the fix for CVE-2016-15059, introduced the defect. Only the XS backend is affected.

Decoding an attacker-supplied punycode label reads and writes freed heap memory.

CVSS v3
8.4
EG Score
8.4HIGHhigh confidence
EG Risk
38
EG Risk 38/100CISA SSVC

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
Severity84% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 22, 2026

Last Modified

September 22, 2026

Vendor Advisories for CVE-2026-74766(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 rangeFix by version rangeDependents
libnet-idn-encode-perl2.500-3, 2.500-5
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libnet-idn-encode-perl2.500-5
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libnet-idn-encode-perl2.500-5
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 28× in last 7d / 60× 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. 2026-10-05 08:18 UTCEG score recompute
  2. 2026-10-05 08:18 UTCGHSA enrichment
  3. 2026-10-04 23:22 UTCEPSS rescore
  4. 2026-10-04 21:10 UTCGHSA enrichment
  5. 2026-10-04 10:02 UTCGHSA enrichment
  6. 2026-10-03 22:55 UTCEG score recompute
  7. 2026-10-03 22:55 UTCGHSA enrichment
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-03 11:48 UTCGHSA enrichment
  10. 2026-10-03 00:26 UTCEG score recompute
  11. 2026-10-03 00:26 UTCGHSA enrichment
  12. 2026-10-02 13:19 UTCGHSA enrichment
  13. 2026-10-02 02:13 UTCEG score recompute
  14. 2026-10-02 02:12 UTCGHSA enrichment
  15. 2026-10-01 19:50 UTCEPSS rescore
  16. 2026-10-01 15:01 UTCGHSA enrichment
  17. 2026-10-01 03:55 UTCGHSA enrichment
  18. 2026-09-30 16:48 UTCEG score recompute
  19. 2026-09-30 16:48 UTCGHSA enrichment
  20. 2026-09-30 05:25 UTCGHSA enrichment
  21. 2026-09-29 18:18 UTCEG score recompute
  22. 2026-09-29 18:18 UTCGHSA enrichment
  23. 2026-09-29 15:24 UTCEPSS rescore
  24. 2026-09-29 07:01 UTCEG score recompute
  25. 2026-09-29 07:00 UTCGHSA enrichment
Show 35 more
  1. 2026-09-28 19:53 UTCEG score recompute
  2. 2026-09-28 19:53 UTCGHSA enrichment
  3. 2026-09-28 13:52 UTCEPSS rescore
  4. 2026-09-28 08:46 UTCGHSA enrichment
  5. 2026-09-27 21:39 UTCEG score recompute
  6. 2026-09-27 21:39 UTCGHSA enrichment
  7. 2026-09-27 13:48 UTCEPSS rescore
  8. 2026-09-27 10:31 UTCGHSA enrichment
  9. 2026-09-26 23:21 UTCEG score recompute
  10. 2026-09-26 23:20 UTCGHSA enrichment
  11. 2026-09-26 15:59 UTCEPSS rescore
  12. 2026-09-26 12:09 UTCGHSA enrichment
  13. 2026-09-26 01:03 UTCEG score recompute
  14. 2026-09-26 01:03 UTCGHSA enrichment
  15. 2026-09-26 00:28 UTCEPSS rescore
  16. 2026-09-25 13:53 UTCGHSA enrichment
  17. 2026-09-25 02:47 UTCGHSA enrichment
  18. 2026-09-24 15:40 UTCEG score recompute
  19. 2026-09-24 15:40 UTCGHSA enrichment
  20. 2026-09-24 14:04 UTCEPSS rescore
  21. 2026-09-24 04:34 UTCEG score recompute
  22. 2026-09-24 04:34 UTCGHSA enrichment
  23. 2026-09-23 17:54 UTCEPSS rescore
  24. 2026-09-23 17:27 UTCGHSA enrichment
  25. 2026-09-23 06:20 UTCGHSA enrichment
  26. 2026-09-22 19:13 UTCEG score recompute
  27. 2026-09-22 19:13 UTCGHSA enrichment
  28. 2026-09-22 16:01 UTCEPSS rescore
  29. 2026-09-22 13:18 UTCGHSA enrichment
  30. 2026-09-22 12:56 UTCEG score recompute▲ 8.40
  31. 2026-09-22 12:56 UTCGHSA enrichment
  32. 2026-09-22 12:55 UTCMITRE cvelistV5CVSS v3 → 8.4 · severity → HIGH
  33. 2026-09-22 08:33 UTCNVD update
  34. 2026-09-22 07:31 UTCEG score recompute
  35. 2026-09-22 07:30 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-74766?
CVE-2026-74766 is a high vulnerability published on September 22, 2026. Net::IDN::Punycode versions from 2.301 before 2.590 for Perl allow a heap use-after-free via a decoded code point that reallocates the output buffer in decode_punycode. The XS backend inserts each decoded code point into the string buffer of the scalar it returns. decode_punycode computes the…
When was CVE-2026-74766 disclosed?
CVE-2026-74766 was first published on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74766 actively exploited?
CVE-2026-74766 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-74766?
CVE-2026-74766 has a CVSS v3.1 base score of 8.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74766?
No fix for CVE-2026-74766 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-74766 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-74766

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