CVE-2026-120757

NameCVE-2026-120757
DescriptionHDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5L__extern_traverse() in src/H5Lexternal.c, the default traversal callback for external links. The callback locates the target file name and object path within the link’s user data using strlen() without validating the buffer against its stored size (udata_size, which was marked unused). A crafted HDF5 file containing an external link whose data is not NULL-terminated, or is too short to hold both strings, causes strlen() to read past the end of the udata heap buffer, and the derived object path pointer may also point outside the buffer. The overrun is unbounded and continues until a zero byte is found. The flaw is triggered when the malicious link is traversed, for example when opening an object through it. An attacker who can get a user or application to access a crafted file can cause a denial of service, and adjacent heap contents may be incorporated into the external file name or object path the library attempts to open.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
hdf5 (PTS)bookworm1.10.8+repack1-1vulnerable
trixie1.14.5+repack-3vulnerable
forky2.2.0+repack-5vulnerable
sid2.2.0+repack-6vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
hdf5source(unstable)(unfixed)unimportant

Notes

https://github.com/HDFGroup/hdf5/pull/6708
https://github.com/HDFGroup/hdf5/commit/8117f4c75fdfb5e759ad73ce62d7ef4584130acd
HDF not covered by security support, see https://bugs.debian.org/1117722

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