CVE-2025-49506: APR-util versions 1.6.3 (and earlier) function apr_password_validate() was not constant-time with regards to h

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HIGH 7.5REMOTEWATCHLISTUPGRADE

CVE-2025-49506 is a high-severity flaw (CVSS 7.5) affecting apr-util. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

APR-util versions 1.6.3 (and earlier) function apr_password_validate() was not constant-time with regards to hashes or passwords comparisons, potentially leaking their content via a side channel timing attack particularly on platforms without crypt() such as Windows, BeOS, NetWare, or Android. Users are recommended to upgrade to version 1.6.4, which fixes this issue.

Why this priority

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

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	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-208
Published	2026-08-06
Last modified	2026-09-29

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-09-29 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-06 15:16 UTCPublished CVE record published
2026-09-29 14:10 UTCUpdated Record last modified

apache apr-util UPGRADE

Affected: >= 1.2.0 and < 1.6.4

Fixed in: 1.6.4

Safe to downgrade to: a release before 1.2.0

1. Check installed version

apt-cache policy apr-util || rpm -q apr-util || apr-util --version

2. UPGRADE to 1.6.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade apr-util

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade apr-util

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 1.2.0 (Debian / Ubuntu)

apt-cache madison apr-util sudo apt install apr-util=<VERSION_BEFORE_1.2.0> sudo apt-mark hold apr-util

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

dnf --showduplicates list apr-util sudo dnf downgrade apr-util-<VERSION_BEFORE_1.2.0> sudo dnf versionlock add apr-util

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-2025-49506?

apr-util: upgrade to 1.6.4. Exact commands for each OS are on this page.

Is CVE-2025-49506 being exploited?

CVE-2025-49506 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-2025-49506 affect?

CVE-2025-49506 affects apr-util. Severity is high (CVSS 7.5). APR-util versions 1.6.3 (and earlier) function apr_password_validate() was not constant-time with regards to hashes or passwords comparisons, potentially leaking their content via a side channel timing attack particularly on platforms witho

How urgent is CVE-2025-49506?

Priority 44/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Windows vulnerabilities · Android vulnerabilities

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References

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