CVE-2015-0843: yubiserver before 0.6 is prone to buffer overflows due to misuse of sprintf.

This month

CRITICAL 9.8REMOTEWATCHLISTDOWNGRADE

CVE-2015-0843 is a critical-severity flaw (CVSS 9.8) affecting yubiserver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

yubiserver before 0.6 is prone to buffer overflows due to misuse of sprintf.

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 61%)
CISA exploited list	No
Weakness	CWE-120
Published	2025-06-26
Last modified	2026-06-17

Publisher (CNA): Debian GNU/Linux · Vendor: debian

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

Am I affected?

Timeline

2025-06-26 22:15 UTCPublished CVE record published
2026-06-17 00:21 UTCUpdated Record last modified

debian yubiserver DOWNGRADE

Affected: 0.2-2 · 0.5-2

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.2-2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.2-2 (Debian / Ubuntu)

apt-cache madison yubiserver sudo apt install yubiserver=<VERSION_BEFORE_0.2-2> sudo apt-mark hold yubiserver

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

dnf --showduplicates list yubiserver sudo dnf downgrade yubiserver-<VERSION_BEFORE_0.2-2> sudo dnf versionlock add yubiserver

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.

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-2015-0843?

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

Is CVE-2015-0843 being exploited?

CVE-2015-0843 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-2015-0843 affect?

CVE-2015-0843 affects yubiserver. Severity is critical (CVSS 9.8). yubiserver before 0.6 is prone to buffer overflows due to misuse of sprintf.

How urgent is CVE-2015-0843?

Priority 54/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2015-0842 CRITICAL 9.8 DOWNGRADE yubiserver before 0.6 is prone to SQL injection issues, potentially leading to an authentication bypass.

References

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