CVE-2026-45271

MEDIUMPre-NVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (3rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.5Exploit: None knownExposed services: Not assessed

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

Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. Picotls implements its own ASN.1 validation helper, which is used by the minicrypto backend while parsing local PKCS#8 private keys. Prior to commit c14231d801407640bc42c2dcf92783409ea6a7c7, the validator recursively descends into constructed ASN.1 elements without enforcing a maximum nesting depth. If an application loads an attacker-supplied private-key file through ptls_minicrypto_load_private_key(), or otherwise calls the public ASN.1 validation API on untrusted DER, a crafted deeply nested ASN.1 structure can exhaust the process stack and crash the application. Note that the libcrypto (OpenSSL) backend does not use the ASN.1 validation helper of picotls, and therefore is immune to this vulnerability. The vulnerability has been addressed in commit c14231d801407640bc42c2dcf92783409ea6a7c7.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

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 (value × EchelonGraph’s weight)
Severity55% × 45%
The EG Score, 5.5 of 10.
Exploitation0.1% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines, and watch for a fix.
EPSS PROB
0.2%
EPSS %ILE
3rd
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system within your standard update timelines, and watch for a fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 21, 2026

Last Modified

September 30, 2026

Advisory Details (2)

Auto-updated Aug 21, 2026
No fix on record yet. Sources: github_commit, github.
GitHub advisoryMentions a patch (unverified)

infinite recursion in the minicrypto ASN.1 decoder · Advisory · h2o/picotls · GitHub

https://github.com/h2o/picotls/security/advisories/GHSA-84f5-m5x2-82q4
GitHub commit

commit c14231d80140 (h2o/picotls)

Fix landed in h2o/picotls commit c14231d80140 — awaiting tagged release

https://github.com/h2o/picotls/commit/c14231d801407640bc42c2dcf92783409ea6a7c7

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 46× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-11 19:46 UTCEG score recompute
  2. 2026-10-11 17:01 UTCEG score recompute
  3. 2026-10-11 14:26 UTCEG score recompute
  4. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  7. 2026-10-09 05:40 UTCEG score recompute
  8. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  9. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  10. 2026-10-07 09:59 UTCEG score recompute
  11. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  12. 2026-10-06 07:48 UTCEG score recompute
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  14. 2026-10-05 05:14 UTCEG score recompute
  15. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  16. 2026-10-04 03:04 UTCEG score recompute
  17. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  18. 2026-10-03 00:53 UTCEG score recompute
  19. 2026-10-01 22:44 UTCEG score recompute
  20. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  21. 2026-09-30 20:02 UTCEG score recompute
  22. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  23. 2026-09-30 08:52 UTCEG score recompute
  24. 2026-09-29 06:42 UTCEG score recompute
  25. 2026-09-28 04:33 UTCEG score recompute
Show 52 more
  1. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  2. 2026-09-27 02:24 UTCEG score recompute
  3. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
  4. 2026-09-25 17:02 UTCEG score recompute
  5. 2026-09-24 12:13 UTCEG score recompute
  6. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  7. 2026-09-23 10:03 UTCEG score recompute
  8. 2026-09-22 07:53 UTCEG score recompute
  9. 2026-09-19 00:00 UTCEG score recompute
  10. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  11. 2026-09-17 21:51 UTCEG score recompute
  12. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  13. 2026-09-16 19:41 UTCEG score recompute
  14. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  15. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  16. 2026-09-15 15:13 UTCEG score recompute
  17. 2026-09-14 12:43 UTCEG score recompute
  18. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  19. 2026-09-13 10:24 UTCEG score recompute
  20. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  21. 2026-09-12 08:14 UTCEG score recompute
  22. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  23. 2026-09-11 06:05 UTCEG score recompute
  24. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  25. 2026-09-09 01:44 UTCEG score recompute
  26. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  27. 2026-09-06 18:36 UTCEG score recompute
  28. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  29. 2026-09-05 16:26 UTCEG score recompute
  30. 2026-09-04 14:17 UTCEG score recompute
  31. 2026-09-02 09:47 UTCEG score recompute
  32. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  33. 2026-09-01 07:37 UTCEG score recompute
  34. 2026-08-31 05:25 UTCEG score recompute
  35. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  36. 2026-08-30 03:15 UTCEG score recompute
  37. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  38. 2026-08-29 01:05 UTCEG score recompute
  39. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  40. 2026-08-27 20:01 UTCEG score recompute
  41. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  42. 2026-08-26 17:51 UTCEG score recompute
  43. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  44. 2026-08-25 15:23 UTCEG score recompute
  45. 2026-08-25 14:35 UTCEG score recompute
  46. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  47. 2026-08-25 03:54 UTCEG score recompute
  48. 2026-08-24 01:44 UTCEG score recompute
  49. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  50. 2026-08-21 21:24 UTCEG score recompute
  51. 2026-08-21 21:05 UTCEG score recomputeFirst assessed: 5.5 MEDIUM
  52. 2026-08-21 21:04 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-45271?
CVE-2026-45271 is a medium-severity vulnerability; its CVE record was published on August 21, 2026. Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. Picotls implements its own ASN.1 validation helper, which is used by the minicrypto backend while parsing local PKCS#8 private keys. Prior to commit…
When was the CVE record for CVE-2026-45271 published?
The CVE record for CVE-2026-45271 was published on August 21, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 30, 2026; the record at its source may have been updated since.
Is CVE-2026-45271 actively exploited?
CVE-2026-45271 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (3rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-45271?
CVE-2026-45271 has a CVSS base score of 5.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-45271?
No fix for CVE-2026-45271 is confirmed yet. Until one is published, restrict network exposure of the affected system — for example, keep it off the internet or limit it to trusted networks — and watch for a fix.

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