Medium · CVSS 6.8CVE-2026-111458

ssldump Heap Buffer Overflow in FAN/1 X.509 Fingerprint FormattingCVE-2026-111458

Answer in brief

CVE-2026-111458 records a Medium severity (CVSS 6.8) vulnerability in ssldump Heap Buffer Overflow in FAN/1 X.509 Fingerprint Formatting. The current sources do not mark it as known exploited. The current feed maps adulau/ssldump (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 16, 2026Updated Oct 16, 2026Source checked Oct 16, 2026First seen by HOL Oct 16, 2026Material review Oct 16, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 6.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps adulau/ssldump (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
adulau/ssldumpgeneric	>=0 <=1.9.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for adulau/ssldump.
Review the reported fix. Source-reported solution: The fix replaces the hardcoded size calculation and unbounded sprintf with a two-step snprintf approach: first computing the exact required output length via snprintf(NULL, 0, format, b64, hex), then allocating precisely that length plus one byte for the null terminator via calloc, and finally writing the formatted string with a bounded snprintf. This eliminates the undersized allocation and guarantees the write never exceeds the allocated buffer.

Evidence timeline and material changes

Published upstream
Oct 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 16, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.