What is CVE-2006-4434?

CVE-2006-4434 is a high-severity vulnerability in Sendmail, classified under Use After Free. CVSS score: 7.5/10. Published 2006-08-29.

How severe is CVE-2006-4434?

High severity. CVSS v3 base score is 7.5 out of 10.

Use After Free in Sendmail

CVE-2006-4434

Use-after-free vulnerability in Sendmail before 8.13.8 allows remote attackers to cause a denial of service (crash) via a long "header line", which causes a previously freed variable to be referenced. NOTE: the original developer has disputed the severity of this issue, saying "The only denial of service that is possible here is to fill up the disk with core dumps if the OS actually generates different core dumps (which is unlikely)... the bug is in the shutdown code (finis()) which leads directly to exit(3), i.e., the process would terminate anyway, no mail delivery or receiption is affected."

Vulnerability class: Use-After-Free

Published 2006-08-29 · last modified 2026-06-16.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.045 (91.3th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 91.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.045 · newest: 0.045 · change: +0.001

Affected products

Sendmail

Weakness classification (CWE)

CWE-416 — Use After Free

References

www.openbsd.org/errata.html (vendor-advisory, Release Notes)
www.attrition.org/pipermail/vim/2006-August/000999.html (mailing-list, Mailing List)
securitytracker.com/id (Patch, VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
secunia.com/advisories/21637 (Patch, Broken Link, Vendor Advisory, third-party-advisory)
www.vupen.com/english/advisories/2006/3994 (vdb-entry, Broken Link, Vendor Advisory)
www.osvdb.org/28193 (vdb-entry, Broken Link)
secunia.com/advisories/21749 (Broken Link, Vendor Advisory, third-party-advisory)
secunia.com/advisories/21700 (Broken Link, Vendor Advisory, third-party-advisory)
www.debian.org/security/2006/dsa-1164 (vendor-advisory, Broken Link)
secunia.com/advisories/21641 (Patch, Broken Link, Vendor Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2006-4434?: CVE-2006-4434 is a high-severity vulnerability in Sendmail, classified under Use After Free. CVSS score: 7.5/10. Published 2006-08-29.
How severe is CVE-2006-4434?: High severity. CVSS v3 base score is 7.5 out of 10.