# CVE-2026-5089: YAML::Syck versions before 1.38 for Perl has an out-of-bounds read

> An out-of-bounds read in YAML::Syck allows attackers to cause denial of service or disclose memory contents via crafted YAML input.

- **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:** 12 May 2026
- **Updated:** 14 May 2026
- **Also known as:** AZL-109511, AZL-86901, BELL-CVE-2026-5089, DEBIAN-CVE-2026-5089, GHSA-jcwf-qrr5-xwq3, MGASA-2026-0148, UBUNTU-CVE-2026-5089, openSUSE-SU-2026:10846-1, openSUSE-SU-2026:20938-1

## What is CVE-2026-5089?

CVE-2026-5089 is a high-severity memory corruption vulnerability in TODDR YAML::Syck, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

YAML::Syck versions before 1.38 for Perl  has an out-of-bounds read.

The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer:

    while ( colon >= ptr && *colon != ':' )
    {
        colon--;
    }
    if ( *colon == ':' ) *colon = '\0';  // colon may be ptr-1 here

When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.

Weakness: CWE-124 (Buffer Underwrite)

## Which versions are affected by CVE-2026-5089?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `perl-YAML-Syck` | openSUSE:Leap 16.0 | All versions | 1.450.0-bp160.2.1 |
| `perl-YAML-Syck` | openSUSE:Tumbleweed | All versions | 1.450.0-4.1 |

## How do I fix CVE-2026-5089?

Upgrade to a fixed version.

## Is CVE-2026-5089 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5089 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5089 and fix it if it is affected.

What it is: CVE-2026-5089 is a high-severity memory corruption vulnerability in TODDR YAML::Syck, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5089 exists.

Affected product: TODDR YAML::Syck. 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-2026-5089/ (Markdown: https://insights.sbomify.com/CVE-2026-5089/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5089
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5089
- OSV: https://osv.dev/vulnerability/CVE-2026-5089

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5089/
Summaries are generated and may contain mistakes; the official description above is the record.