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CVE-2017-16943· NVD / CVE Program· CNA mitre

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a

Noroxi assessment

Priority: Plan (action score 53/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 47.1% (FIRST EPSS); higher than 98.8% 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. No special conditions are required; it is repeatable.
  • Fixed version: exim4 (Debian:12) 4.89-12; exim4 (Debian:9) 4.89-2+deb9u2; exim (openSUSE:Leap 15.2) 4.94.2-lp152.8.3.1.
  • Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Add it to your regular patch cycle. Upgrade to exim4 (Debian:12) 4.89-12; exim4 (Debian:9) 4.89-2+deb9u2; exim (openSUSE:Leap 15.2) 4.94.2-lp152.8.3.1 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

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via vectors involving BDAT commands.

CriticalCVSS 9.8 · v3.0—Proof of concept Fix available
Published
Nov 25, 2017
Updated
Jun 16, 2026
EPSS
47.1% · 99th percentile

Report tools

JSON

Action score

53

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
14 / 30 · 47.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi 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.

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Affected 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.

VendorProduct
eximexim
debiandebian linux

Using exim? Add it to your stack and be the first to know about CVEs like this one. (Email server)

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • exim exim4.88
  • exim exim4.89

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12exim4before 4.89-124.89-12
Debian:9exim4before 4.89-2+deb9u24.89-2+deb9u2
openSUSE:Leap 15.2eximbefore 4.94.2-lp152.8.3.14.94.2-lp152.8.3.1
openSUSE:Tumbleweedeximbefore 4.94.2-4.24.94.2-4.2
SUSE:Package Hub 15 SP1eximbefore 4.94.2-bp151.2.4.14.94.2-bp151.2.4.1
SUSE:Package Hub 15 SP1libspf2before 1.2.10-bp151.4.11.2.10-bp151.4.1
SUSE:Package Hub 15 SP2eximbefore 4.94.2-bp152.6.4.14.94.2-bp152.6.4.1
SUSE:Package Hub 15 SP2libspf2before 1.2.10-bp152.5.11.2.10-bp152.5.1

Same product

exim: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-10149A flaw was found in Exim versions 4.87 to 4.91 (inclusive).KEV
    99Now
  • CVE-2018-6789An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1.KEV
    94Now
  • 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 KEV
    91Now
  • CVE-2019-16928Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than CVE-2019-15846.KEV
    81Now
  • CVE-2010-4345Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of the exim user account to specify an alternate confiKEV
    66This week
  • CVE-2025-26794Exim 4.98 before 4.98.1, when SQLite hints and ETRN serialization are used, allows remote SQL injection.
    62This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:exim44.89-12 · Debian:12Package registry (OSV)
opensuse:exim4.94.2-lp152.8.3.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:exim4.94.2-bp151.2.4.1 · SUSE:Package Hub 15 SP1Package registry (OSV)
suse:libspf21.2.10-bp151.4.1 · SUSE:Package Hub 15 SP1Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02018-11-20

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.

  1. Published
  2. First PoC+359 d
  3. TodayOct 13, 2026+3244 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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.
  • 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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (8 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records