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CVE-2010-4344 — Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70…

Key facts

CVE-2010-4344 is a Critical (9.8) vulnerability: Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2022-03-25), confirming active exploitation in the wild.

Actively exploited — on the CISA KEV catalog

CVE-2010-4344 is listed on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2022-03-25), confirming exploitation in the wild. Federal remediation deadline: 2022-04-15. Prioritise patching and deploy the detection and prevention rules below.
CVE CVE-2010-4344
Severity Critical (9.8)
CISA KEV Actively exploited (added 2022-03-25)
Detection / prevention —
PoC poc.py
Source 2010/CVE-2010-4344/

Details

English | 한국어

Description

Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70 allows remote attackers to execute arbitrary code via an SMTP session that includes two MAIL commands in conjunction with a large message containing crafted headers, leading to improper rejection logging.

Vulnerability Details

Property Value
CVE ID CVE-2010-4344
Type RCE
CVSS Score 9.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2010/CVE-2010-4344/poc.py

Usage

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start

# Clone and navigate to CVE directory
cd CVE-2010-4344

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints

Application URL Status
Vulnerable App http://localhost:8080 Shows vulnerability
Patched App http://localhost:8081 Demonstrates fix

Directory Structure

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References

  • ftp://ftp.exim.org/pub/exim/ChangeLogs/ChangeLog-4.70
  • http://atmail.com/blog/2010/atmail-6204-now-available/
  • http://bugs.exim.org/show_bug.cgi?id=787
  • http://git.exim.org/exim.git/commit/24c929a27415c7cfc7126c47e4cad39acf3efa6b
  • http://lists.exim.org/lurker/message/20101210.164935.385e04d0.en.html
  • http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00003.html
  • http://openwall.com/lists/oss-security/2010/12/10/1
  • http://secunia.com/advisories/40019
  • http://secunia.com/advisories/42576
  • http://secunia.com/advisories/42586
  • http://secunia.com/advisories/42587
  • http://secunia.com/advisories/42589
  • http://www.cpanel.net/2010/12/exim-remote-memory-corruption-vulnerability-notification-cve-2010-4344.html
  • http://www.debian.org/security/2010/dsa-2131
  • http://www.exim.org/lurker/message/20101207.215955.bb32d4f2.en.html
  • http://www.kb.cert.org/vuls/id/682457
  • http://www.metasploit.com/modules/exploit/unix/smtp/exim4_string_format
  • http://www.openwall.com/lists/oss-security/2021/05/04/7
  • http://www.osvdb.org/69685
  • http://www.redhat.com/support/errata/RHSA-2010-0970.html
  • http://www.securityfocus.com/archive/1/515172/100/0/threaded
  • http://www.securityfocus.com/bid/45308
  • http://www.securitytracker.com/id?1024858
  • http://www.theregister.co.uk/2010/12/11/exim_code_execution_peril/
  • http://www.ubuntu.com/usn/USN-1032-1
  • http://www.vupen.com/english/advisories/2010/3171
  • http://www.vupen.com/english/advisories/2010/3172
  • http://www.vupen.com/english/advisories/2010/3181
  • http://www.vupen.com/english/advisories/2010/3186
  • http://www.vupen.com/english/advisories/2010/3204
  • http://www.vupen.com/english/advisories/2010/3246
  • http://www.vupen.com/english/advisories/2010/3317
  • https://bugzilla.redhat.com/show_bug.cgi?id=661756
  • ftp://ftp.exim.org/pub/exim/ChangeLogs/ChangeLog-4.70
  • http://atmail.com/blog/2010/atmail-6204-now-available/
  • http://bugs.exim.org/show_bug.cgi?id=787
  • http://git.exim.org/exim.git/commit/24c929a27415c7cfc7126c47e4cad39acf3efa6b
  • http://lists.exim.org/lurker/message/20101210.164935.385e04d0.en.html
  • http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00003.html
  • http://openwall.com/lists/oss-security/2010/12/10/1
  • http://secunia.com/advisories/40019
  • http://secunia.com/advisories/42576
  • http://secunia.com/advisories/42586
  • http://secunia.com/advisories/42587
  • http://secunia.com/advisories/42589
  • http://www.cpanel.net/2010/12/exim-remote-memory-corruption-vulnerability-notification-cve-2010-4344.html
  • http://www.debian.org/security/2010/dsa-2131
  • http://www.exim.org/lurker/message/20101207.215955.bb32d4f2.en.html
  • http://www.kb.cert.org/vuls/id/682457
  • http://www.metasploit.com/modules/exploit/unix/smtp/exim4_string_format
  • http://www.openwall.com/lists/oss-security/2021/05/04/7
  • http://www.osvdb.org/69685
  • http://www.redhat.com/support/errata/RHSA-2010-0970.html
  • http://www.securityfocus.com/archive/1/515172/100/0/threaded
  • http://www.securityfocus.com/bid/45308
  • http://www.securitytracker.com/id?1024858
  • http://www.theregister.co.uk/2010/12/11/exim_code_execution_peril/
  • http://www.ubuntu.com/usn/USN-1032-1
  • http://www.vupen.com/english/advisories/2010/3171
  • http://www.vupen.com/english/advisories/2010/3172
  • http://www.vupen.com/english/advisories/2010/3181
  • http://www.vupen.com/english/advisories/2010/3186
  • http://www.vupen.com/english/advisories/2010/3204
  • http://www.vupen.com/english/advisories/2010/3246
  • http://www.vupen.com/english/advisories/2010/3317
  • https://bugzilla.redhat.com/show_bug.cgi?id=661756
  • https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2010-4344

Generated by PoC Generator on 2026-07-08T04:50:29.043374248

Frequently asked questions

What is CVE-2010-4344?

CVE-2010-4344 is a Critical (9.8) vulnerability: Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2022-03-25), confirming active exploitation in the wild.

How do I detect CVE-2010-4344?

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2010-4344?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

Is CVE-2010-4344 actively exploited?

Yes. CVE-2010-4344 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2022-03-25, which means it has been exploited in the wild. CISA set a federal remediation deadline of 2022-04-15. Prioritise patching and deploy the detection and prevention rules above.

For authorized security testing and research only. See the full source and NVD record.