# CVE-2026-5435: Potential buffer overflow in ns_sprintrrf TSIG handling path

> Out-of-bounds write in glibc TSIG handling allows attackers to execute arbitrary code or cause denial of service.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Apr 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-84599, BELL-CVE-2026-5435, DEBIAN-CVE-2026-5435, ECHO-53d2-a97b-142d, GHSA-32rw-r8mp-pw42, MINI-2w45-2j8f-x4g4, MINI-5699-2qf6-m8cp, MINI-vq5r-m254-8qq7, ROOT-OS-DEBIAN-11-CVE-2026-5435, ROOT-OS-DEBIAN-12-CVE-2026-5435, ROOT-OS-DEBIAN-13-CVE-2026-5435, UBUNTU-CVE-2026-5435

## What is CVE-2026-5435?

CVE-2026-5435 is a high-severity memory corruption vulnerability in Gnu Glibc, published on 28 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail to enforce the caller-supplied buffer length, and can result in an out-of-bounds write when printing TSIG records.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-5435?

It affects 1 product.


Products: Gnu Glibc.

## How do I fix CVE-2026-5435?

Apply the vendor's patch.

## Is CVE-2026-5435 being exploited?

There is no known exploitation of CVE-2026-5435 in the wild and no public exploit code.

## Other vulnerabilities in Gnu Glibc

- [CVE-2026-5450](https://insights.sbomify.com/CVE-2026-5450/): scanf %mc off-by-one heap buffer overflow (critical 9.8)
- [CVE-2023-25139](https://insights.sbomify.com/CVE-2023-25139/): Memory corruption in n/a (critical 9.8)
- [CVE-1999-0199](https://insights.sbomify.com/CVE-1999-0199/): Other in n/a (critical 9.8)
- [CVE-2019-1010022](https://insights.sbomify.com/CVE-2019-1010022/): Security feature bypass in glibc (critical 9.8)
- [CVE-2005-3590](https://insights.sbomify.com/CVE-2005-3590/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5435 and fix it if it is affected.

What it is: CVE-2026-5435 is a high-severity memory corruption vulnerability in Gnu Glibc, published on 28 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5435 in the wild and no public exploit code.

Affected product: Gnu Glibc. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5435/ (Markdown: https://insights.sbomify.com/CVE-2026-5435/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5435
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5435
- OSV: https://osv.dev/vulnerability/CVE-2026-5435

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5435/
Summaries are generated and may contain mistakes; the official description above is the record.