CVE-2026-29199: phpBB before 3.3.16 is vulnerable to Host Header Injection that can lead to password rest link poisoning

Q: How do I fix CVE-2026-29199?

phpbb: upgrade to 3.3.16. Exact commands for each OS are on this page.

Q: Is CVE-2026-29199 being exploited?

CVE-2026-29199 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-29199 affect?

CVE-2026-29199 affects phpbb. Severity is high (CVSS 8.1). phpBB before 3.3.16 is vulnerable to Host Header Injection that can lead to password rest link poisoning. When force_server_vars is disabled, the servers hostname may be extracted from the HTTP Host header which is used to generate the pass

Routine

HIGH 8.1UPGRADE

CVE-2026-29199 is a high-severity flaw (CVSS 8.1) affecting phpbb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

phpBB before 3.3.16 is vulnerable to Host Header Injection that can lead to password rest link poisoning. When force_server_vars is disabled, the servers hostname may be extracted from the HTTP Host header which is used to generate the password reset link URL. An attacker who can manipulate the Host header (e.g. through misconfigured host setup or missing header validation by the webserver) can cause password reset emails to contain a link pointi

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-640
Published	2026-05-04
Last modified	2026-06-17

Publisher (CNA): HackerOne · Vendor: phpbb

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

Am I affected?

Timeline

2026-05-04 07:15 UTCPublished CVE record published
2026-06-17 10:29 UTCUpdated Record last modified

phpbb phpbb UPGRADE

Affected: < 3.3.16

Fixed in: 3.3.16

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.3.16 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade phpbb

Note

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

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-2026-29199?

phpbb: upgrade to 3.3.16. Exact commands for each OS are on this page.

Is CVE-2026-29199 being exploited?

CVE-2026-29199 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-2026-29199 affect?

CVE-2026-29199 affects phpbb. Severity is high (CVSS 8.1). phpBB before 3.3.16 is vulnerable to Host Header Injection that can lead to password rest link poisoning. When force_server_vars is disabled, the servers hostname may be extracted from the HTTP Host header which is used to generate the pass

How urgent is CVE-2026-29199?

Priority 32/100. High severity

Related CVEs

CVE-2025-70811 MEDIUM 4.3 DOWNGRADE Cross Site Request Forgery vulnerability in Phpbb phbb3 v.3.3.15 allows a local attacker to execute arbitrary
CVE-2025-70810 HIGH 8.8 DOWNGRADE Cross Site Request Forgery vulnerability in Phpbb phbb3 v.3.3.15 allows a local attacker to execute arbitrary

References

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