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PatchSiren cyber security CVE debrief

CVE-2016-7972 Fedoraproject CVE debrief

CVE-2016-7972 is a high-severity availability issue in libass versions before 0.13.4. According to the NVD description, the check_allocations function in libass/ass_shaper.c can be driven into a memory allocation failure by remote input, resulting in denial of service. The supplied record rates the issue CVSS 3.0 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), which means it is remotely reachable, requires no privileges or user interaction, and primarily affects service availability.

Vendor
Fedoraproject
Product
CVE-2016-7972
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2017-03-03
Original CVE updated
2026-05-13
Advisory published
2017-03-03
Advisory updated
2026-05-13

Who should care

Organizations that ship or embed libass, especially subtitle-rendering stacks, media players, transcoding services, and Linux distributions or appliance images that still contain libass 0.13.3 or earlier. Systems mapped in the supplied corpus include Fedora 23/24/25 and openSUSE Leap 42.1 / openSUSE 13.2, so distro maintainers and operators of those environments should verify patched package levels.

Technical summary

The vulnerability is in libass/ass_shaper.c check_allocations. The source corpus says that, before libass 0.13.4, certain remote inputs can cause a memory allocation failure that leads to denial of service. The record does not provide a confirmed exploit path or payload details, so the safe defensive takeaway is that input handling in the subtitle shaping/allocation path can be abused to crash or otherwise interrupt service availability. Weakness mapping in NVD is CWE-399 (resource management / resource consumption related issue).

Defensive priority

High. This is a remotely reachable, no-authentication, no-user-interaction availability issue with a published fix. Even though the impact is DoS rather than code execution, services that process untrusted media or subtitle content can face outage risk, so patching should be prioritized on internet-facing or high-availability systems.

Recommended defensive actions

  • Upgrade libass to 0.13.4 or later, or apply the vendor-provided backport for your distribution.
  • Verify whether your applications bundle libass directly or inherit it from the OS package manager.
  • Check distro advisories and package announcements for patched Fedora, openSUSE, or other downstream builds.
  • Inventory media-processing and subtitle-rendering services that may ingest untrusted content and confirm their libass version.
  • If immediate patching is not possible, reduce exposure by limiting untrusted input sources and monitoring for process crashes or repeated restarts.
  • Confirm remediation by comparing installed package versions against the fixed release and vendor security notes.

Evidence notes

This debrief is based only on the supplied NVD/CVE corpus and the linked official or vendor-adjacent references. The corpus states the issue was published on 2017-03-03 and later modified on 2026-05-13; that modification date is record metadata, not the vulnerability date. The corpus does not include proof of active exploitation, KEV listing, or ransomware association. The provided references support that a fix existed in libass 0.13.4 and that downstream advisories were issued.

Official resources

CVE published 2017-03-03. The supplied record was later modified on 2026-05-13. Upstream and downstream patch references in the corpus indicate the fix was available by libass 0.13.4.