PatchTheCVECVE-2010-4344: Exim Heap-Based Buffer Overflow Vulnerability
CVE-2010-4344 is a critical-severity flaw (CVSS 9.8) affecting exim, opensuse, debian linux, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Critical severity
- EPSS top 1%: very likely to be exploited
- Exploited in the wild (CISA KEV)
- Public exploit reference
- CISA SSVC: automatable with total technical impact
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 71.7% (top 1%) |
| CISA exploited list | Yes, fix due 2022-04-15 |
| Weakness | CWE-787 |
| Published | 2010-12-14 |
| Last modified | 2026-06-16 |
Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Exploited Added to the CISA Known Exploited Vulnerabilities list
- Deadline CISA due date for US federal agencies to patch
- Updated Record last modified
Exact fixes by distribution
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
- Exploit-DB: Exim 4.63 - Remote Command Execution
- Exploit-DB: Exim4 < 4.69 - string_format Function Heap Buffer Overflow (Metasploit)
- Metasploit: Exim4 string_format Function Heap Buffer Overflow
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2010-4344?
exim: upgrade to 4.70; opensuse: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2010-4344 being exploited?
Yes. CVE-2010-4344 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.
What does CVE-2010-4344 affect?
CVE-2010-4344 affects exim, opensuse, debian linux. Severity is critical (CVSS 9.8). 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 c
How urgent is CVE-2010-4344?
Priority 100/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist
Software pages
Ubuntu vulnerabilities · Debian vulnerabilities · Exim vulnerabilities
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- CVE-2026-94057 MEDIUM 4.0 UPGRADE Exim before 4.100.1 allows SMTP smuggling in which the received message does not match any sent message, and i