# CVE-2026-19542: GNU C Library tdelete stack-based buffer overflow

Source: https://junglewise.ai/threats/cve-2026-19542-gnu-c-library-tdelete-stack-based-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-14. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-19542 · Severity: medium · CVSS 5.6 · Published 2026-09-14

The GNU C Library's tdelete function (used for tree data structure operations) contains a stack buffer overflow vulnerability that can crash applications. While the vulnerability requires extremely specific conditions—a tree with at least a million nodes at particular depths—and the overflow is difficult to control, it poses a denial-of-service risk to any application using the tsearch/tdelete functions with large datasets. Red Hat and other Linux distributors have not identified actively exploited cases in common applications.

Technologies: [Gnu C Library](https://junglewise.ai/threats/technologies/c-library). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-19542 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-19542 being exploited in the wild.

**How severe is CVE-2026-19542?** Medium severity, with a CVSS score of 5.6, published 14 September 2026.

**Which products and versions are affected?** Gnu C Library 2.1 to 2.44.

**Is there a fix for CVE-2026-19542?** A patch was published on 2026-08-14: glibc 2.45 (commit e2789c46e3bfdcd67a82bea9946b315c179e83d3) Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-19542 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-19542?** Check whether you run Gnu C Library at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a stack-based buffer overflow in the tdelete function's tree rebalancing logic. The tdelete implementation maintains an explicit stack (via alloca) of parent nodes for rebalancing; during tree descent, two specific rebalancing branches push entries without checking array capacity, causing an out-of-bounds write when the stack is exactly full. Exploitation requires a tree at exactly depth 40 (or multiples of 20 beyond that), implying at least one million nodes. The attack vector is network-adjacent (requires an attacker to drive large numbers of insertions/deletions through an application), though the overflow value itself (a tree node pointer) is not directly attacker-controlled. The vulnerability affects glibc 2.1–2.44; a fix was released in glibc 2.45 and backported to earlier stable branches, replacing alloca with a static maximum-sized allocation.

## Affected products

- GNU C Library 2.1 to 2.44

## Timeline

- 2026-08-11: disclosed
- 2026-08-14: patched: glibc 2.45 (commit e2789c46e3bfdcd67a82bea9946b315c179e83d3)

## References

- [https://sourceware.org/bugzilla/show_bug.cgi?id=34506](https://sourceware.org/bugzilla/show_bug.cgi?id=34506)
- [https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0018](https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0018)

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