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🛡️ CVE-2026-48840 on Ubuntu — exim4

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Exim 4.88 before 4.99.4, in some proxy configurations, mishandles certain short payloads, leading to disclosure of uninitialized stack memory values to a client.

Distribution advisory

This page covers CVE-2026-48840 as tracked by Ubuntu, for the package exim4. The fix is available in version 4.99.1-1ubuntu1.3; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

UBUNTU-CVE-2026-48840 is classified as CWE-839: Numeric Range Comparison Without Minimum Check. The product checks a value to ensure that it is less than or equal to a maximum, but it does not also verify that the value is greater than or equal to the minimum.

Affected software

UBUNTU-CVE-2026-48840 is recorded against 1 package.

  • exim4 (fixed in 4.99.1-1ubuntu1.3)

Timeline and source

Published on 29 May 2026 and last revised on 4 June 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
www.exim.org (Report)
ubuntu.com (Advisory)
ubuntu.com (Advisory)

Other advisories for this package

exim4 has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-839: Numeric Range Comparison Without Minimum Check) in other software:

CVE-2026-48840 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-05-29
Updated 2026-08-20
Modified 2026-06-04
Fix URL N/A

Affected Packages

Software From version Fixed in
exim4 — 4.99.1-1ubuntu1.3

Vulnerability Monitoring

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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