CVE-2016-9963: Exim before 4.87.1 might allow remote attackers to obtain the private DKIM signing key via vectors related to log files and bounce messages.
Noroxi assessment
Priority: Monitor (action score 24/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 3% (FIRST EPSS); higher than 87.9% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: exim4 (Debian:12) 4.88~RC6-2; exim4 (Debian:7) 4.80-7+deb7u4; exim4 (Debian:8) 4.84.2-2+deb8u2.
Low priority for now. Upgrade to exim4 (Debian:12) 4.88~RC6-2; exim4 (Debian:7) 4.80-7+deb7u4; exim4 (Debian:8) 4.84.2-2+deb8u2 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
- Published
- Feb 1, 2017
- Updated
- Jun 16, 2026
- EPSS
- 3.0% · 87th percentile
- CWE
- CWE-320
Report tools
Action score
24
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 3.0%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| exim | exim | cpe:2.3:a:exim:exim |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Using exim? Add it to your stack and be the first to know about CVEs like this one. (Email server)
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- exim eximup to 4.87 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | exim4 | before 4.88~RC6-2 | 4.88~RC6-2 |
| Debian:7 | exim4 | before 4.80-7+deb7u4 | 4.80-7+deb7u4 |
| Debian:8 | exim4 | before 4.84.2-2+deb8u2 | 4.84.2-2+deb8u2 |
| openSUSE:Tumbleweed | exim | before 4.94.2-4.2 | 4.94.2-4.2 |
Same product
exim: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-10149A flaw was found in Exim versions 4.87 to 4.91 (inclusive).KEV99Now
- CVE-2018-6789An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1.KEV94Now
- CVE-2010-4344Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70 allows remote attackers to execute arbitrary code…KEV91Now
Published before and after this one in the same product
- ← EarlierCVE-2014-2972Sep 4, 2014 · expand.c in Exim before 4.83 expands mathematical comparisons twice, which allows local users to gain privileges and execute arbitrary…18Monitor
- ← EarlierCVE-2016-1531Apr 7, 2016 · Exim before 4.86.2, when installed setuid root, allows local users to gain privileges via the perl_startup argument.40Plan
- Later →CVE-2017-1000369Jun 19, 2017 · Exim supports the use of multiple "-p" command line arguments which are malloc()'ed and never free()'ed, used in conjunction with other…16Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:exim4 | 4.88~RC6-2 · Debian:12 | Package registry (OSV) |
| opensuse:exim | 4.94.2-4.2 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-320 · Key Management ErrorsCVSS vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log (1)
- Fix✗ → ✓
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References
Show all references (5 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.