[KEV] Out-of-Bounds Write in Exim Internet Mailer (CVE-2019-16928)
Summary
Out-of-bounds write in Exim Internet Mailer (CVE-2019-16928). Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited.
Original description
The description as published by the source.
Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than CVE-2019-15846. There is a heap-based buffer overflow in string_vformat in string.c involving a long EHLO command.
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2019-16928 has been found in Exim Internet Mailer.
Successful exploitation can lead to full system takeover.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Exim Internet Mailer CVE-2019-16928" on the vendor's site.
CVE-2019-16928 (Exim Internet Mailer) — CWE-787
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Listed in CISA KEV — actively exploited, treat as top priority.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds write (CWE-787) exists in Exim Internet Mailer.
Check the vendor advisory for the affected versions of Exim Internet Mailer.
Severity: High. Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited in the wild, treat as top priority.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Exim Internet Mailer を使っているサービスとバージョンを洗い出す。
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2Consider incident declaration escalate
Notify SOC / on-callCISA KEV登録済 = 実環境で悪用が観測されている。侵入の兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2019-16928 exim4 Fixed in: 4.92.2-3
References
- advisory NVD
- advisory openwall.com
- advisory openwall.com
- advisory lists.exim.org
- advisory lists.fedoraproject.org
- advisory lists.fedoraproject.org
- advisory lists.fedoraproject.org
- advisory seclists.org
- advisory security.gentoo.org
- advisory usn.ubuntu.com
- advisory debian.org
- patch bugs.exim.org
- patch git.exim.org
- report openwall.com
- report openwall.com
- web cisa.gov