CVE-2026-55967: AES-GCM encryption/decryption with extremely large cumulative single message sizes (>64 GiB) were not properly

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-55967 is a high-severity flaw (CVSS 7.5) affecting wolfssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

AES-GCM encryption/decryption with extremely large cumulative single message sizes (>64 GiB) were not properly rejected by the streaming APIs, allowing counter wrap, keystream reuse, and consequent plaintext recovery.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-323
Published	2026-06-25
Last modified	2026-10-24

Publisher (CNA): wolfSSL Inc. · Vendor: wolfssl

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-25 18:16 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

wolfssl wolfssl UPGRADE

Affected: >= 4.8.0 and < 5.9.2

Fixed in: 5.9.2

Safe to downgrade to: a release before 4.8.0

1. Check installed version

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

2. UPGRADE to 5.9.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade wolfssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade wolfssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.8.0 (Debian / Ubuntu)

apt-cache madison wolfssl sudo apt install wolfssl=<VERSION_BEFORE_4.8.0> sudo apt-mark hold wolfssl

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list wolfssl sudo dnf downgrade wolfssl-<VERSION_BEFORE_4.8.0> sudo dnf versionlock add wolfssl

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.

Exact fixes by distribution

Fedora 46 · sugar-calculator · FIXED · 47-14.fc46 · FEDORA-2026-38eeb9e279 · source

sudo dnf upgrade --advisory=FEDORA-2026-38eeb9e279

Fedora ELN · selinux-policy · FIXED · 45.23-1.eln159 · FEDORA-2026-3668c969a2 · source

sudo dnf upgrade --advisory=FEDORA-2026-3668c969a2

Debian 12 · wolfssl · FIXED · 5.5.4-2+deb12u3

sudo apt update && sudo apt install --only-upgrade wolfssl dpkg --compare-versions "$(dpkg-query -W -f='${Version}' wolfssl)" ge "5.5.4-2+deb12u3" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · wolfssl · FIXED · 5.7.2-0.1+deb13u2

sudo apt update && sudo apt install --only-upgrade wolfssl dpkg --compare-versions "$(dpkg-query -W -f='${Version}' wolfssl)" ge "5.7.2-0.1+deb13u2" && echo PATCHED || echo STILL-VULNERABLE

Alpine 3.24 · wolfssl · FIXED · wolfssl-5.9.2-r0

apk add --upgrade wolfssl apk info -v wolfssl

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/wolfSSL/wolfssl/pull/10709
Write-up: www.wolfssl.com/docs/security-vulnerabilities/

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-2026-55967?

wolfssl: upgrade to 5.9.2. Exact commands for each OS are on this page.

Is CVE-2026-55967 being exploited?

CVE-2026-55967 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-2026-55967 affect?

CVE-2026-55967 affects wolfssl. Severity is high (CVSS 7.5). AES-GCM encryption/decryption with extremely large cumulative single message sizes (>64 GiB) were not properly rejected by the streaming APIs, allowing counter wrap, keystream reuse, and consequent plaintext recovery.

How urgent is CVE-2026-55967?

Priority 33/100. High severity; Remotely exploitable, no login, no user action

References

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