CVE-2025-11933: DoS Vulnerability in wolfSSL TLS 1.3 CKS Extension
Vulnerability summary
CVE-2025-11933 is a medium (CVSS 6.5) Improper Input Validation vulnerability in wofssl wolfssl. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 39.2% of scored vulnerabilities.
Not severe (CVSS 2.3, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Timeline
- 21-11-2025PublishedVulnerability first disclosed.
- 08-12-2025Last modifiedVulnerability information updated.
Description
Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL 5.8.2 and earlier on multiple platforms allows a remote unauthenticated attacker to potentially cause a denial-of-service via a crafted ClientHello message with duplicate CKS extensions.
CVSS metrics
7 scores · 5 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated2.3LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L
- NVDNIST2.3LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · AlpineEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.45%
Chance of exploitation in the next 30 days
Percentile
39%
Versus all other CVEs
30-day change
Increase +0.03 pp
From 0.42% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Alpine1 product
- wolfssl≥ 5.8.2, < 5.9.1-r0 | ≥ 5.8.2, < 5.8.4-r0
Debian1 product
- wolfsslAll versions (No fix recorded)
Ubuntu1 product
- wolfsslAll versions (No fix recorded)
Wofssl1 product
- wolfssl≥ 3.12.0, < 5.8.4
Wolfssl1 product
- wolfssl≥ 5.8.2, < 5.8.4
5 vendors · 5 products
