CVE-2026-55556

highpriority · track · 0EPSS 0.009 · 58 %ileDE
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.85% (58th) EPSS
CVSS 8.2 · high
Is it mine?
2 products
Check your exposure
Who says so?
1 sources
cert_bund

EPSS · scored 2026-10-27

Rsyslog is a rocket-fast system for log processing. From 8.2110.0 until 8.2604.0, the optional imhttp module's parse_auth_header function in contrib/imhttp/imhttp.c allocates a zero-byte heap buffer with calloc(0, len) when an HTTP Basic Authorization value exceeds its fixed work buffer, then passes that pointer to apr_base64_decode. An unauthenticated remote attacker can send an oversized encoded credential to an imhttp endpoint configured for Basic Authentication, causing decoded data to overwrite adjacent heap memory before credential validation. Deployments that do not install, load, and use imhttp with Basic Authentication are not affected. The demonstrated impact is a process crash that interrupts log collection, and code execution has not been demonstrated. This issue is fixed in version 8.2604.0.

01

cvss

Technical severity, 0–10. One row per scoring source.

8.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.6–8.2

v4.08.2highCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · security-advisories@github.com
v4.04.6mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-122US
04

affected products (2)

Products and version ranges known to be affected.

05

advisories (1)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-2045rsyslog: Schwachstelle ermöglicht Denial of ServiceDeutsch2026-06-23csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann eine Schwachstelle in rsyslog ausnutzen, um einen Denial of Service Angriff durchzuführen.

06

sources

Which sources assert this record, and when.

cert_bundNVDCVE.orgMITRE
published 2026-09-18modified 2026-09-24
07

references (5) nvd

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan