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."

Published: 2006-08-29 Last update: 2026-04-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2006-4434 is rated Moderate Risk (59.6/100): CVSS High severity, with high exploitation likelihood (EPSS 7.03%, 91th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2006-4434

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 9.29% 7.03% -2.27%
2 2025-12-27 7.03% 9.29% +2.27%
3 2025-10-28 — 7.03% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2006-4434

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2006-4434

OS Trackers for CVE-2006-4434

vendor priority summary link
alpine — CVE-2006-4434: no source package rows; 0 state rows across 0 repos (none); fixed 0, open 0. https://security.alpinelinux.org/vuln/CVE-2006-4434
debian medium CVE-2006-4434 medium priority: Debian including 1 source packages (sendmail), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2006-4434
redhat — — https://access.redhat.com/security/cve/CVE-2006-4434
ubuntu medium CVE-2006-4434 medium priority: Ubuntu including 1 source packages (sendmail), 9 status rows across 9 suites (dapper, edgy, feisty, gutsy, hardy, intrepid, jaunty, karmic, upstream): released 8, ignored 1. https://ubuntu.com/security/CVE-2006-4434

Vendor comments (NVD) for CVE-2006-4434

  • Red Hat (2006-08-30T00:00:00)

    This flaw causes a crash but does not result in a denial of service against Sendmail and is therefore not a security issue.

Affected software / configurations for CVE-2006-4434

Vendor Product Version Raw CPE
sendmail sendmail < 8.13.8 cpe:2.3:a:sendmail:sendmail:*:*:*:*:*:*:*:*

References for CVE-2006-4434

URL Tags
http://secunia.com/advisories/21637 Broken Link Patch Vendor Advisory
http://secunia.com/advisories/21641 Broken Link Patch Vendor Advisory
http://secunia.com/advisories/21696 Broken Link Vendor Advisory
http://secunia.com/advisories/21700 Broken Link Vendor Advisory
http://secunia.com/advisories/21749 Broken Link Vendor Advisory
http://secunia.com/advisories/22369 Broken Link Vendor Advisory
http://securitytracker.com/id?1016753 Broken Link Patch Third Party Advisory VDB Entry
http://sunsolve.sun.com/search/document.do?assetkey=1-26-102664-1 Broken Link
http://www.attrition.org/pipermail/vim/2006-August/000999.html Mailing List
http://www.debian.org/security/2006/dsa-1164 Broken Link
http://www.mandriva.com/security/advisories?name=MDKSA-2006:156 Broken Link
http://www.novell.com/linux/security/advisories/2006_21_sr.html Broken Link
http://www.openbsd.org/errata.html#sendmail3 Release Notes
http://www.openbsd.org/errata38.html#sendmail3 Third Party Advisory
http://www.osvdb.org/28193 Broken Link
http://www.securityfocus.com/bid/19714 Broken Link Patch Third Party Advisory VDB Entry
http://www.sendmail.org/releases/8.13.8.html Release Notes
http://www.vupen.com/english/advisories/2006/3393 Broken Link Vendor Advisory
http://www.vupen.com/english/advisories/2006/3994 Broken Link Vendor Advisory
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