CVE-2020-36430 : libass 0.15.x before 0.15.1 has a heap-based buffer overflow in decode

libass 0.15.x before 0.15.1 has a heap-based buffer overflow in decode_chars (called from decode_font and process_text) because the wrong integer data type is used for subtraction.

Published 2021-07-20 07:15:08

Updated 2022-12-09 18:35:55

Source MITRE

View at NVD, CVE.org

Vulnerability category: OverflowMemory Corruption

Products affected by CVE-2020-36430

Fedoraproject » Fedora » Version: 34
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
Matching versions
Libass Project » Libass
Versions from including (>=) 0.15.0 and before (<) 0.15.1
cpe:2.3:a:libass_project:libass:*:*:*:*:*:*:*:*
Matching versions

Exploit prediction scoring system (EPSS) score for CVE-2020-36430

EPSS FAQ

0.11%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 43 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-36430

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
6.8	MEDIUM	AV:N/AC:M/Au:N/C:P/I:P/A:P	8.6	6.4	NIST
Access Vector: Network Access Complexity: Medium Authentication: None Confidentiality Impact: Partial Integrity Impact: Partial Availability Impact: Partial
7.8	HIGH	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	1.8	5.9	NIST
Attack Vector: Local Attack Complexity: Low Privileges Required: None User Interaction: Required Scope: Unchanged Confidentiality: High Integrity: High Availability: High

CWE ids for CVE-2020-36430

CWE-787 Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

Assigned by: nvd@nist.gov (Primary)

References for CVE-2020-36430

https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26674

26674 - libass:libass_fuzzer: Heap-buffer-overflow in decode_chars - oss-fuzz
Issue Tracking;Patch;Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6JUXFQUJ32GWG5E46A63DFDCYJAF3VU6/

[SECURITY] Fedora 34 Update: libass-0.15.2-1.fc34 - package-announce - Fedora Mailing-Lists
Mailing List;Third Party Advisory
https://github.com/libass/libass/commit/017137471d0043e0321e377ed8da48e45a3ec632

decode_font: fix subtraction broken by change to unsigned type · libass/libass@0171374 · GitHub
Patch;Third Party Advisory
https://security.gentoo.org/glsa/202208-13

libass: Denial of service (GLSA 202208-13) — Gentoo security
Third Party Advisory
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/libass/OSV-2020-2099.yaml

oss-fuzz-vulns/OSV-2020-2099.yaml at main · google/oss-fuzz-vulns · GitHub
Third Party Advisory

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Vulnerability Details : CVE-2020-36430

Products affected by CVE-2020-36430

Exploit prediction scoring system (EPSS) score for CVE-2020-36430

CVSS scores for CVE-2020-36430

CWE ids for CVE-2020-36430

References for CVE-2020-36430