CVE-2026-19542

NameCVE-2026-19542
DescriptionCalling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application. The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.
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
glibc (PTS)bookworm2.36-9+deb12u14vulnerable
bookworm (security)2.36-9+deb12u7vulnerable
trixie2.41-12+deb13u4vulnerable
forky, sid2.43-6fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
glibcsource(unstable)2.43-4

Notes

[trixie] - glibc <no-dsa> (Minor issue)
[bookworm] - glibc <postponed> (Minor issue)
https://sourceware.org/bugzilla/show_bug.cgi?id=34506
Fixed by: https://sourceware.org/git/?p=glibc.git;a=commit;h=e2789c46e3bfdcd67a82bea9946b315c179e83d3
https://sourceware.org/git/?p=glibc.git;a=blob;f=advisories/GLIBC-SA-2026-0018

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