A Use After Free vulnerability in svg_dev_text_span_as_paths_defs function in source/fitz/svg-device.c in Artifex Software MuPDF 1.16.0 allows remote attackers to cause a denial of service via opening of a crafted PDF file.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-7825-1 advisory.

    It was discovered that MuPDF incorrectly managed memory, resulting in a memory leak. An attacker could     possibly use this issue to cause a denial of service. This issue only affected Ubuntu 18.04 LTS.
    (CVE-2018-1000036)

    It was discovered that MuPDF could enter an infinite loop when parsing certain PDF files. An attacker     could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 18.04 LTS.
    (CVE-2018-10289)

    It was discovered that MuPDF incorrectly managed memory, possibly leading to a segmentation fault. An     attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 18.04     LTS. (CVE-2018-16647, CVE-2018-16648)

    It was discovered that MuPDF contained a use-after-free vulnerability. An attacker could possibly use this     issue to cause a denial of service. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.
    (CVE-2020-21896)

    It was discovered that MuPDF incorrectly managed memory, resulting in a memory leak. An attacker could     possibly use this issue to cause a denial of service or obtain sensitive information. This issue only     affected Ubuntu 20.04 LTS. (CVE-2020-26683)

    Maxim Mishechkin, Vitalii Akolzin, Shamil Kurmangaleev, Denis Straghkov, Fedor Nis'kov and Ivan Gulakov     discovered that MuPDF incorrectly managed memory under certain circumstances, leading to a double-free. An     attacker could possibly use this to cause a denial of service. This issue only affected Ubuntu 16.04 LTS,     Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2021-3407)

    Xuwei Liu discovered that MuPDF may perform an out-of-bounds write under certain circumstances. An     attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 18.04     LTS and Ubuntu 20.04 LTS. (CVE-2021-37220)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 11 host has packages installed that are affected by a vulnerability as referenced in the dla-4278 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4278-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                           Chris Lamb     August 22, 2025                               https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : mupdf     Version        : 1.17.0+ds1-2+deb11u1     CVE ID         : CVE-2020-21896

    It was discovered that there was a potential use after free     vulnerability in mupdf, a lightweight PDF viewer. This could have     allowed remote attackers to cause a denial of service attack when     opening a maliciously-crafted PDF file.

    For Debian 11 bullseye, this problem has been fixed in version     1.17.0+ds1-2+deb11u1.

    We recommend that you upgrade your mupdf packages.

    For the detailed security status of mupdf please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/mupdf

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
270675	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : MuPDF vulnerabilities (USN-7825-1)	Nessus	Ubuntu Local Security Checks	medium
253666	Debian dla-4278 : libmupdf-dev - security update	Nessus	Debian Local Security Checks	medium

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CVE-2020-21896

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