CVE-2026-111458 ssldump Heap Buffer Overflow in FAN/1 X.509 Fingerprint Formatting
A heap buffer overflow in ssldump allows attackers to execute arbitrary code or cause denial of service via crafted pcap files when FAN/1 fingerprinting is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-111458?
CVE-2026-111458 is a medium-severity memory corruption vulnerability in adulau ssldump, published on 16 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-111458?
How do I fix CVE-2026-111458?
No fix has been published for CVE-2026-111458 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-111458 being exploited?
There is no known exploitation of CVE-2026-111458 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-111458, GHSA-px2j-96c7-vxc7, UBUNTU-CVE-2026-111458.