CVE-2019-11757

When following the values prototype chain, it was possible to retain a reference to a locale, delete it, and subsequently reference it. This resulted in a use-after-free and a potentially exploitable crash. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1577107
• https://security.gentoo.org/glsa/202003-10
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2019-33/
• https://www.mozilla.org/security/advisories/mfsa2019-34/
• https://www.mozilla.org/security/advisories/mfsa2019-35/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1577107
• https://security.gentoo.org/glsa/202003-10
• https://usn.ubuntu.com/4335-1/
• https://www.mozilla.org/security/advisories/mfsa2019-33/
• https://www.mozilla.org/security/advisories/mfsa2019-34/
• https://www.mozilla.org/security/advisories/mfsa2019-35/