CVE-2020-28011: Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S.
Noroxi assessment
Priority: Monitor (action score 31/100)
- 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: 0.39% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: exim (Alpine:v3.13) 4.94.2-r0; exim4 (Debian:10) 4.92-8+deb10u6; exim4 (Debian:12) 4.94.2-1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to exim (Alpine:v3.13) 4.94.2-r0; exim4 (Debian:10) 4.92-8+deb10u6; exim4 (Debian:12) 4.94.2-1 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
Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S. This may cause privilege escalation from exim to root.
- Published
- May 6, 2021
- Updated
- Jun 16, 2026
- EPSS
- 0.3% · 33th percentile
- CWE
- CWE-787
Report tools
Action score
31
Low priority for now.
- CVSS
- 31 / 40 · 7.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
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 |
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 exim4.00 and later · before 4.94.2
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.13 | exim | from 4.00 · before 4.94.2-r0 | 4.94.2-r0 |
| Debian:10 | exim4 | before 4.92-8+deb10u6 | 4.92-8+deb10u6 |
| Debian:12 | exim4 | before 4.94.2-1 | 4.94.2-1 |
| Debian:9 | exim4 | before 4.89-2+deb9u8 | 4.89-2+deb9u8 |
| openSUSE:Leap 15.2 | exim | before 4.94.2-lp152.8.3.1 | 4.94.2-lp152.8.3.1 |
| openSUSE:Tumbleweed | exim | before 4.94.2-4.2 | 4.94.2-4.2 |
| SUSE:Package Hub 15 SP1 | exim | before 4.94.2-bp151.2.4.1 | 4.94.2-bp151.2.4.1 |
| SUSE:Package Hub 15 SP1 | libspf2 | before 1.2.10-bp151.4.1 | 1.2.10-bp151.4.1 |
| SUSE:Package Hub 15 SP2 | exim | before 4.94.2-bp152.6.4.1 | 4.94.2-bp152.6.4.1 |
| SUSE:Package Hub 15 SP2 | libspf2 | before 1.2.10-bp152.5.1 | 1.2.10-bp152.5.1 |
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-2020-28009May 6, 2021 · Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads that are accompanied by…31Monitor
- ← EarlierCVE-2020-28010May 6, 2021 · Exim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname…31Monitor
- Later →CVE-2020-28012May 6, 2021 · Exim 4 before 4.94.2 allows Exposure of File Descriptor to Unintended Control Sphere because rda_interpret uses a privileged pipe that…31Monitor
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 |
|---|---|---|
| alpine:exim | 4.94.2-r0 · Alpine:v3.13 | Package registry (OSV) |
| debian:exim4 | 4.94.2-1 · Debian:12 | Package registry (OSV) |
| opensuse:exim | 4.94.2-lp152.8.3.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| suse:exim | 4.94.2-bp151.2.4.1 · SUSE:Package Hub 15 SP1 | Package registry (OSV) |
| suse:libspf2 | 1.2.10-bp151.4.1 · SUSE:Package Hub 15 SP1 | 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.
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-21-0383 · May 5, 2021(Exim E-Posta Sunucusu Güvenlik Zafiyeti)
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
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-787 · Out-of-bounds WriteCVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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
Vendor advisories and official records. Exploit/PoC links are deliberately left out.