Bug 2553943 (CVE-2026-111458)

Summary: CVE-2026-111458 ssldump: ssldump: Arbitrary code execution via heap-based buffer overflow in certificate fingerprint formatting
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in ssldump. A heap-based buffer overflow allows an attacker to achieve arbitrary code execution or cause a Denial of Service (DoS) through an application crash. The issue occurs because memory is miscalculated and undersized when formatting certificate fingerprints. An attacker can exploit this vulnerability by convincing a user to inspect a maliciously crafted network packet capture file.
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Bug Depends On: 2554364, 2554367    
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Description OSIDB Bzimport 2026-10-16 05:41:23 UTC 
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.