{"id":"UBUNTU-CVE-2026-39855","details":"osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When page hash processing is performed on a PE file, the function subtracts hdrsize from pagesize without first validating that pagesize \u003e= hdrsize. If a malicious PE file sets SizeOfHeaders (hdrsize) larger than SectionAlignment (pagesize), the subtraction underflows and produces a very large unsigned length. The code allocates a zero-filled buffer of pagesize bytes and then attempts to hash pagesize - hdrsize bytes from that buffer. After the underflow, this results in an out-of-bounds read from the heap and can crash the process. The vulnerability can be triggered while signing a malicious PE file with page hashing enabled (-ph), or while verifying a malicious signed PE file that already contains page hashes. Verification of an already signed file does not require the verifier to pass -ph. This vulnerability is fixed in 2.13.","modified":"2026-04-16T09:13:14Z","published":"2026-04-09T17:16:00Z","upstream":["CVE-2026-39855"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-39855"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-39855"},{"type":"REPORT","url":"https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-76vv-x5rr-q3mr"},{"type":"REPORT","url":"https://github.com/mtrojnar/osslsigncode/commit/2a5409b7c4b6c6fad2b093531e8fea6cf08e1568"},{"type":"REPORT","url":"https://github.com/mtrojnar/osslsigncode/releases/tag/2.13"}],"affected":[{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/osslsigncode@1.7.1-1?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"osslsigncode","binary_version":"1.7.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}},{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/osslsigncode@1.7.1-3?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.1-2build1","1.7.1-2ubuntu1","1.7.1-3"],"ecosystem_specific":{"binaries":[{"binary_name":"osslsigncode","binary_version":"1.7.1-3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}},{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/osslsigncode@2.0-1?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"osslsigncode","binary_version":"2.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}},{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/osslsigncode@2.2-1ubuntu1?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1-1","2.2-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"osslsigncode","binary_version":"2.2-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}},{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/osslsigncode@2.8-2?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5-4","2.8-2"],"ecosystem_specific":{"binaries":[{"binary_name":"osslsigncode","binary_version":"2.8-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}},{"package":{"name":"osslsigncode","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/osslsigncode@2.9-2?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.9-2"],"ecosystem_specific":{"binaries":[{"binary_version":"2.9-2","binary_name":"osslsigncode"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39855.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}