No exploitation reportedFix available

CVE-2023-4639

Q: Is CVE-2023-4639 actively exploited?

Active exploitation of CVE-2023-4639 has not been confirmed. Its EPSS score was 1.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2023-4639?

CVE-2023-4639 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

No exploitation reported by the sources we read.

Published2024-11-17
Fixed in2.3.11.Final · 2.2.30.Final
WeaknessCWE-444

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A flaw was found in Undertow, which incorrectly parses cookies with certain value-delimiting characters in incoming requests. This issue could allow an attacker to construct a cookie value to exfiltrate HttpOnly cookie values or spoof arbitrary additional cookie values, leading to unauthorized data access or modification. The main threat from this flaw impacts data confidentiality and integrity.

Timeline

dates in UTC

2024-11-1711:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-4639?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-4639?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV

undertow-core

Branch	Affected	Fixed in	Source
2.3	≥ 2.3.0.Alpha1, < 2.3.11.Final	2.3.11.Final	OSV
2.2	< 2.2.30.Final	2.2.30.Final	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update undertow-core to 2.3.11.Final · 2.2.30.Final

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2024-11-17
OpenCVESSVC decisionnone—
CNACVSS 3.17.4read 2026-10-23
CNAweakness (CWE)CWE-444read 2026-10-23
FIRST EPSSEPSS score1.1 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2024-11-17
Last Modified: 2026-06-17
NVD status: Deferred

Frequently asked questions

What is CVE-2023-4639?

Is CVE-2023-4639 actively exploited?

Active exploitation of CVE-2023-4639 has not been confirmed. Its EPSS score was 1.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-4639?

CVE-2023-4639 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

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