---
id: CVE-2026-111458
title: >-
  The fanx_fingerprint function in ssl/sslxprint.c of ssldump allocates a heap
  buffer for formatting FAN/1 X.509 certificate fingerprints
summary: >-
  The fanx_fingerprint function in ssl/sslxprint.c of ssldump allocates a heap
  buffer for formatting FAN/1 X.509 certificate fingerprints. The allocation
  size is computed as strlen(b64) + strlen(hex) + 31, but the format string
  "fan1:x509:…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-787
vendor: Red Hat
product: ssldump
affected:
  - ssldump <= 1.9.0
published: '2026-10-16'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T20:04:29.760'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-111458'
references:
  - url: >-
      https://github.com/adulau/ssldump/commit/8ad55683cc0186600c085d33be5a5b627db78467
    label: 5a6e4751-2f3f-4070-9419-94fb35b644e8
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-111458.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-111458'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-111458'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00094
epssPercentile: 0.00578
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T12:30:41.664327Z'
cvssSource: vendor
scores:
  vendor: 7.8
  cna: 6.8
ingestedAt: '2026-10-16T06:00:00.397Z'
---

## Overview

The fanx_fingerprint function in ssl/sslxprint.c of ssldump allocates a heap buffer for formatting FAN/1 X.509 certificate fingerprints. The allocation size is computed as strlen(b64) + strlen(hex) + 31, but the format string "fan1:x509:server:passive:%s:sha256:%s" contains 33 fixed characters in addition to the two variable-length fields and a null terminator, requiring strlen(b64) + strlen(hex) + 34 bytes. This miscalculation results in a 3-byte heap-based buffer overflow on every invocation of the function with valid inputs. The overflow occurs because sprintf writes the full formatted string into the undersized heap buffer without bounds checking. An attacker who can supply a crafted pcap file containing a TLS X.509 certificate to a user running ssldump with FAN/1 fingerprinting enabled (for example with the -j -N options) can trigger the overflow. The resulting heap corruption may lead to denial of service through a crash or, in a worst-case scenario, arbitrary code execution in the context of the user running ssldump. The vulnerability is deterministic and requires no special privileges beyond the ability to provide input to the tool.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-111458.json)