CVE-2026-88359Medium· 6.5▾ TwilightPoC available

libfyaml 0.9.6 contains a stack exhaustion vulnerability in fy_atom_iter_format()

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score48/ 100 · Moderate

impact 35.8 · likelihood 0.1 · exploitation 12

⚡ Agent-ready:Raw markdown ↗JSON ↗

Proof of concept

A public proof-of-concept already exists for this vulnerability — see Exploit availability below.

…

Published

Sep 24, 2026

Updated

Sep 25, 2026

CVSS

6.5

Vendor

Red Hat

Product

—

CWE

CWE-770

Depth score

48 · Moderate

EPSS

0.30% · p22

Platforms

—

Source

NVD

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Scores by source

NVD 6.5 · CISA ADP 6.5 · Vendor 6.2

CISA SSVC

decided 2026-09-25

Exploitation: poc
Automatable: no
Technical impact: partial

Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.

EPSS history

Exploit-prediction probability, daily snapshots since Sep 26.

0.2% → 0.3%▲ 0.1%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

8 events · 32 days

Sep 24, 2026Published
Disclosed via NVD
Sep 25, 2026Record revised
Last analysed / modified upstream
Sep 25, 2026CVSS changed
— → 6.2
Sep 25, 2026Severity changed
none → medium
Sep 25, 2026Public exploit observed
Exploit / PoC code exists
Sep 25, 2026CVSS changed
6.2 → 6.5
Sep 26, 2026EPSS first tracked
0.2%
Oct 26, 2026EPSS peak
0.2% → 0.3%

Red Hat CWE-770 #nvd #cve.org #csaf #vex #red-hat #exploit-available

Full technical detail▾

Overview

libfyaml 0.9.6 contains a stack exhaustion vulnerability in fy_atom_iter_format(). When processing a specially crafted YAML document containing a very large literal or folded block scalar, the function repeatedly grows an internal buffer using alloca() inside a loop. The allocated stack memory is not released until the function returns, causing cumulative stack growth that can exceed the process stack limit and result in SIGSEGV and denial of service.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

Red Hat VEX · updated 2026-09-24 · vex

References

Change history

Field changes observed since this record was first indexed.

Sep 25, 2026CVSS 6.2 → 6.5
Sep 25, 2026Public exploit / PoC published
Sep 25, 2026CVSS — → 6.2
Sep 25, 2026Severity none → medium

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd#cve.org#csaf#vex#red-hat#exploit-available

← Back to feed