Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.
CVE-2026-3549
CRITICALNVD 9.89.8—Trending — 4 sources updated this week
EchelonGraph scoreMEDIUM confidence
Score 9.8 from GitHub Security Advisory (severity: HIGH) published 2026-03-19. the CNA's CVSS baseline 8.3; sources differ by 1.5.
Triggered by: GitHub Security Advisory CVSS
Sources: cna:wolfssl, ghsa
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- 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 computedSeverity98% × 45%Exploitation0% × 40%Automatability100% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 39%
- KEV
- Not listed
Published
March 19, 2026
Last Modified
June 17, 2026
Advisory Details (1)
Auto-updated Jul 27, 2026Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr
Static code analysis fixes
Fix merged in wolfSSL/wolfssl PR #9817 on 2026-02-26 — awaiting tagged release
https://github.com/wolfSSL/wolfssl/pull/9817Vendor Advisories for CVE-2026-3549(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× 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.
- 2026-07-27 14:13 UTCEPSS rescore
- 2026-07-27 12:51 UTCEG score recompute
- 2026-07-27 12:51 UTCGHSA enrichment
- 2026-07-27 12:50 UTCOSV refresh
Frequently asked(5)
What is CVE-2026-3549?
CVE-2026-3549 is a critical vulnerability published on March 19, 2026. Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.
When was CVE-2026-3549 disclosed?
CVE-2026-3549 was first published in the National Vulnerability Database on March 19, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3549 actively exploited?
CVE-2026-3549 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 60.8% of all scored CVEs.
What is the CVSS score of CVE-2026-3549?
CVE-2026-3549 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-3549?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3549, 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
Explore the affected products and dependency analysis for CVE-2026-3549
Is Your Infrastructure Affected by CVE-2026-3549?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.