CVE-2026-6679: DTLS 1.3 ACK serialization heap buffer overflow via integer truncation
Vulnerability summary
CVE-2026-6679 is a high (CVSS 8.8) Integer Overflow or Wraparound vulnerability in wolfssl. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 43.2% of scored vulnerabilities.
Severe, CVSS 8.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Timeline
- 25-06-2026PublishedVulnerability first disclosed.
- 26-06-2026Last modifiedVulnerability information updated.
Description
A heap buffer overflow could occur in the DTLS 1.3 ACK serialization path before the connecting peer is authenticated. The buffer overflow was due to an integer truncation when computing the length of the ACK record-number list, causing an undersized buffer to be allocated and then overrun. This affects builds using DTLS 1.3 and wolfSSL version 5.9.0 and earlier. A fix was added to the 5.9.1 release.
CVSS metrics
7 scores · 5 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- NVDNIST8.8HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/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 · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.51%
Chance of exploitation in the next 30 days
Percentile
43%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.51% 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 cause- CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
- CWE-197Numeric Truncation ErrorTruncation errors occur when a primitive is cast to a primitive of a smaller size and data is lost in the conversion.
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Alpine1 product
- wolfssl≥ 5.4.0, < 5.9.2-r0
Debian1 product
- wolfsslAll versions (No fix recorded)
Ubuntu1 product
- wolfsslAll versions (No fix recorded)
Wolfssl1 product
- wolfssl≥ 5.4.0, ≤ 5.9.0 | ≥ 5.4.0, < 5.9.1
4 vendors · 4 products
