CVE-2026-39856
CVE-2026-39856 is a medium-severity vulnerability in Osslsigncode Project Osslsigncode with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.
Key facts
- Severity: Medium (CVSS 3.x base score 5.5)
- EPSS exploit prediction: 0% (4th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-20946
- Weakness: CWE-125
- Affected product: Osslsigncode Project Osslsigncode
- Published:
- Last modified:
Description
osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an out-of-bounds read vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When processing PE sections for page hashing, the function uses PointerToRawData and SizeOfRawData values from section headers without validating that the referenced region lies within the mapped file. An attacker can craft a PE file with section headers that point beyond the end of the file. When osslsigncode computes page hashes for such a file, it may attempt to hash data from an invalid memory region, causing an out-of-bounds read and potentially crashing 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.
Frequently asked questions
- What is CVE-2026-39856?
- osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an out-of-bounds read vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When processing PE sections for page hashing, the function uses PointerToRawData and SizeOfRawData values from section headers without validating that the referenced region lies within the mapped file. An attacker can craft a PE file with section headers that point beyond the end of the file. When osslsigncode computes page hashes for such a file, it may attempt to hash data from an invalid memory region, causing an out-of-bounds read and potentially crashing 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.
- How severe is CVE-2026-39856?
- CVE-2026-39856 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2026-39856 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-39856?
- CVE-2026-39856 affects Osslsigncode Project Osslsigncode. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-39856?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-39856 have an EU (EUVD) identifier?
- Yes. CVE-2026-39856 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20946.
- When was CVE-2026-39856 published?
- CVE-2026-39856 was published on 2026-04-09 and last updated on 2026-06-17.
References
- https://github.com/mtrojnar/osslsigncode/commit/92f8761b4770f76a36731969b5040ce3b9a09570
- https://github.com/mtrojnar/osslsigncode/releases/tag/2.13
- https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-rjrx-chvw-8jw8
Affected products (1)
- cpe:2.3:a:osslsigncode_project:osslsigncode:*:*:*:*:*:*:*:*
More vulnerabilities in Osslsigncode Project Osslsigncode
- CVE-2025-70888 — Critical (CVSS 9.8): An issue in mtrojnar Osslsigncode affected at v2.10 and before allows a remote attacker to escalate privileges via the…
- CVE-2026-39853 — High (CVSS 7.8): osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow…
- CVE-2023-36377 — High (CVSS 7.8): Buffer Overflow vulnerability in mtrojnar osslsigncode v.2.3 and before allows a local attacker to execute arbitrary…
- CVE-2026-39855 — Medium (CVSS 5.5): osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow…
All CVEs affecting Osslsigncode Project Osslsigncode →
Other CWE-125 (Out-of-bounds Read) vulnerabilities
- CVE-2026-24826 — Critical (CVSS 10.0): Out-of-bounds Write, Divide By Zero, NULL Pointer Dereference, Use of Uninitialized Resource, Out-of-bounds Read,…
- CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
- CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
- CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
- CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
- CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…