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Fencer Vulns
high 7.5

CVE-2017-12963 json

There is an illegal address access in Sass::Eval::operator() in eval.cpp of LibSass 3.4.5, leading to a remote denial of service attack.

published 2017-08-18 9 y ago modified 2026-06-17 4 mo ago also EUVD-2017-4484

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

There is an illegal address access in Sass::Eval::operator() in eval.cpp of LibSass 3.4.5, leading to a remote denial of service attack. NOTE: this is similar to CVE-2017-11555 but remains exploitable after the vendor's CVE-2017-11555 fix (available from GitHub after 2017-07-24).

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2017-12963 updated

libsass: Multiple vulnerabilities

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.23% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.