CyberSecBulletin
CVE-2026-39879NVD status: Deferred

syslog-ng: Improper Neutralization of Escape, Meta, or Control Sequences

Published Updated By the CyberSecBulletin desk

CVE-2026-39879 is a high-severity improper neutralization of escape, meta, or control sequences vulnerability in syslog-ng, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected syslog-ng versions: < 4.12. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of syslog-ng you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Syslog-ngsyslog-ng< 4.12Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. Scored by CNA (github.com).

Official description

Due to a missing sanitization call in [`afsql_dd_run_query`](https://github.com/syslog-ng/syslog-ng/blob/649e6e18e3459fb4467000a88dfb12fa97f9719c/modules/afsql/afsql.c#L219), syslog-ng before 4.12 are vulnerable to SQL injection from an untrusted source. This is not part of the default configuration, the SQL driver has to be manually configured. Fixes are in syslog-ng 4.12, syslog-ng Premium Edition 8.2 and syslog-ng Store Box 7.8

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Escape, Meta, or Control Sequences

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component.

How developers prevent this class of flaw

  • Developers should anticipate that escape, meta and control characters/sequences will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
  • While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
  • Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

More Improper Neutralization of Escape, Meta, or Control Sequences vulnerabilities (CWE-150)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in syslog-ng

All syslog-ng vulnerabilities

Recent Improper Neutralization of Escape, Meta, or Control Sequences vulnerabilities

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