CVE-2021-28021: Buffer overflow vulnerability in function stbi__extend_receive in stb_image.h in stb 2.26 via a crafted JPEG f

This month

HIGH 7.8WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2021-28021 is a high-severity flaw (CVSS 7.8) affecting stb, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer overflow vulnerability in function stbi__extend_receive in stb_image.h in stb 2.26 via a crafted JPEG file.

Why this priority

High severity
Public exploit reference
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.4% (top 27%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-10-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · stb project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-10-15 16:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

stb project stb DOWNGRADE

Affected: 2.26

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.26

1. Check installed version

apt-cache policy stb || rpm -q stb || stb --version

2. No fixed release: DOWNGRADE to a release before 2.26 (Debian / Ubuntu)

apt-cache madison stb sudo apt install stb=<VERSION_BEFORE_2.26> sudo apt-mark hold stb

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list stb sudo dnf downgrade stb-<VERSION_BEFORE_2.26> sudo dnf versionlock add stb

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

fedoraproject fedora MITIGATE

Affected: 34 · 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-28021?

stb: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-28021 being exploited?

CVE-2021-28021 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-28021 affect?

CVE-2021-28021 affects stb, fedora, debian linux. Severity is high (CVSS 7.8). Buffer overflow vulnerability in function stbi__extend_receive in stb_image.h in stb 2.26 via a crafted JPEG file.

How urgent is CVE-2021-28021?

Priority 56/100. High severity; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2022-28048 HIGH 8.8 DOWNGRADE MITIGATE STB v2.27 was discovered to contain an integer shift of invalid size in the component stbi__jpeg_decode_block_

References

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