CVE-2026-42505

🔶 medium

Summary

Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello.

CVSS Score

5.3

Medium

EPSS Score

0.4

Exploit Probability

Published Date

2026-07-08

First Seen: 2026-07-09

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 19.5% of all 338,292 vulnerabilities in our database.

#272,300

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jul 8, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

Coia Prant (github.com/rbqvq)

SSVC data provided by CISA

Last Modified 2026-07-13

Source NVD 🔗

CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CWE IDs (Weakness Types)

CWE-201

📦 Affected Products 3

Vendor	Product	Status	Affected Versions
golang	go	Affected	< 1.25.12
golang	go	Affected	> 1.26.0 < 1.26.5
golang	go	Affected	v1.27

🔗 References 4

https://go.dev/cl/775960

Patch

https://go.dev/issue/79282

Issue Tracking Patch

https://groups.google.com/g/golang-announce/c/OrmQE_...

Mailing List Release Notes Vendor Advisory

https://pkg.go.dev/vuln/GO-2026-5856

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-39822	⚠️ high	7.8	0.2	On Unix systems, opening a file in an os.Root improperly follows symlinks to locations outside of the Root when the fina...	2026-07-08
CVE-2023-54365	⚠️ high	7.5	0.6	Traefik before 2.10.5 and 3.0.0-beta4 is affected by a denial-of-service vulnerability in HTTP/2 request handling inheri...	2026-06-23
CVE-2026-33811	⚠️ high	7.5	0.8	When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a...	2026-05-07
CVE-2026-33814	⚠️ high	7.5	0.8	When processing HTTP/2 SETTINGS frames, transport will enter an infinite loop of writing CONTINUATION frames if it recei...	2026-05-07
CVE-2026-39820	⚠️ high	7.5	0.8	Well-crafted inputs reaching ParseAddress, ParseAddressList, and ParseDate were able to trigger excessive CPU exhaustion...	2026-05-07
CVE-2026-42499	⚠️ high	7.5	0.8	Pathological inputs could cause DoS through consumePhrase when parsing an email address according to RFC 5322.	2026-05-07

These CVEs affect the same products