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high · CVSS 7.5

CVE-2026-78002

Rsyslog: rsyslog: denial of service via heap buffer overflow in rainerscript replace() function

Published 27 Aug 2026 · Source updated 5 Nov 2026 · Retrieved 2026-11-05 15:04 UTC

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What happened?

A flaw was found in rsyslog. An unauthenticated remote attacker can trigger a heap buffer overflow in the RainerScript `replace()` function by sending specially crafted syslog messages. This vulnerability arises from an incorrect buffer size calculation during string replacement, causing memory corruption. Successful exploitation can lead to a denial of service (DoS) for the affected system.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
SoftwareVersion informationFixed version
rsyslogRed Hatunaffected: 0:8.2510.0-5.el10_2.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2412.0-1.el10_0.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-15.el8_10.3 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.1911.0-7.el8_4.5 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.1911.0-7.el8_4.5 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-7.el8_6.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-7.el8_6.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-13.el8_8.1 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-13.el8_8.1 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2510.0-2.el9_8.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2102.0-113.el9_2.3 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2310.0-4.el9_4.2 to < *See vendor advisory
rsyslogRed Hatunaffected: 0:8.2412.0-1.el9_6.2 to < *See vendor advisory
rhui5/haproxy-rhel9Red Hatunaffected: 1790241900 to < *See vendor advisory
rsyslogRed HatDefault status: unaffectedSee vendor advisory
rsyslog7Red HatDefault status: unaffectedSee vendor advisory
rsyslogRed HatDefault status: affectedSee vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

  1. Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
  2. Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
  3. Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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