CVE-2020-12417

Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in memory corruption and a potentially exploitable crash. Note: this issue only affects Firefox on ARM64 platforms. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00023.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00026.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1640737
• https://security.gentoo.org/glsa/202007-09
• https://security.gentoo.org/glsa/202007-10
• https://usn.ubuntu.com/4421-1/
• https://www.mozilla.org/security/advisories/mfsa2020-24/
• https://www.mozilla.org/security/advisories/mfsa2020-25/
• https://www.mozilla.org/security/advisories/mfsa2020-26/