CVE-2026-26740: Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the

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HIGH 8.2REMOTEDOWNGRADE

CVE-2026-26740 is a high-severity flaw (CVSS 8.2) affecting giflib. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the EGifGCBToExtension overwriting an existing Graphic Control Extension block without validating its allocated size.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 49%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-03-18
Last modified	2026-07-23

Publisher (CNA): MITRE · Vendor: giflib project

Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-18 18:16 UTCPublished CVE record published
2026-07-23 12:17 UTCUpdated Record last modified

giflib project giflib DOWNGRADE

Affected: 5.2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.2.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.2.2 (Debian / Ubuntu)

apt-cache madison giflib sudo apt install giflib=<VERSION_BEFORE_5.2.2> sudo apt-mark hold giflib

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

dnf --showduplicates list giflib sudo dnf downgrade giflib-<VERSION_BEFORE_5.2.2> sudo dnf versionlock add giflib

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.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:33501] Important: giflib security update 2026-07-01

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-2026-26740?

giflib: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-26740 being exploited?

CVE-2026-26740 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-2026-26740 affect?

CVE-2026-26740 affects giflib. Severity is high (CVSS 8.2). Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the EGifGCBToExtension overwriting an existing Graphic Control Extension block without validating its allocated size.

How urgent is CVE-2026-26740?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-48161 HIGH 7.1 DOWNGRADE Buffer Overflow vulnerability in GifLib Project GifLib v.5.2.1 allows a local attacker to obtain sensitive inf
CVE-2026-23868 MEDIUM 5.1 UPGRADE Giflib contains a double-free vulnerability that is the result of a shallow copy in GifMakeSavedImage and inco
CVE-2024-45993 MEDIUM 6.5 DOWNGRADE Giflib Project v5.2.2 is vulnerable to a heap buffer overflow via gif2rgb.

References

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