CVE-2026-77214 libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer
Heap buffer over-read in libexpat allows attackers to disclose adjacent heap memory, defeating ASLR and aiding further exploitation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77214?
CVE-2026-77214 is a high-severity memory corruption vulnerability in libexpat, published on 7 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives.
Weakness: CWE-125
Which versions are affected by CVE-2026-77214?
Linux distribution packages (4)
expat Red Hat:hummingbird:1 | All versions | 0:2.8.5-1.2.hum1 |
expat-devel Red Hat:hummingbird:1 | All versions | 0:2.8.5-1.2.hum1 |
expat-static Red Hat:hummingbird:1 | All versions | 0:2.8.5-1.2.hum1 |
expat openSUSE:Tumbleweed | All versions | 2.9.0-1.1 |
How do I fix CVE-2026-77214?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-77214 being exploited?
There is no known exploitation of CVE-2026-77214 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-77214, AZL-106728, AZL-107228, BELL-CVE-2026-77214, CLSA-2026-1792993465, DEBIAN-CVE-2026-77214 and 9 more.