CVE-2022-37797: In lighttpd 1.4.65, mod_wstunnel does not initialize a handler function pointer if an invalid HTTP request (we

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HIGH 7.5REMOTEWATCHLISTDOWNGRADEMITIGATE

CVE-2022-37797 is a high-severity flaw (CVSS 7.5) affecting lighttpd, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In lighttpd 1.4.65, mod_wstunnel does not initialize a handler function pointer if an invalid HTTP request (websocket handshake) is received. It leads to null pointer dereference which crashes the server. It could be used by an external attacker to cause denial of service condition.

Why this priority

High severity
Public exploit reference
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	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-476
Published	2022-09-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · lighttpd

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

Am I affected?

Timeline

2022-09-12 15:15 UTCPublished CVE record published
2026-06-17 04:55 UTCUpdated Record last modified

lighttpd lighttpd DOWNGRADE

Affected: 1.4.65

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4.65

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.4.65 (Debian / Ubuntu)

apt-cache madison lighttpd sudo apt install lighttpd=<VERSION_BEFORE_1.4.65> sudo apt-mark hold lighttpd

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

dnf --showduplicates list lighttpd sudo dnf downgrade lighttpd-<VERSION_BEFORE_1.4.65> sudo dnf versionlock add lighttpd

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.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2022-37797?

lighttpd: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2022-37797 being exploited?

CVE-2022-37797 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-2022-37797 affect?

CVE-2022-37797 affects lighttpd, debian linux. Severity is high (CVSS 7.5). In lighttpd 1.4.65, mod_wstunnel does not initialize a handler function pointer if an invalid HTTP request (websocket handshake) is received. It leads to null pointer dereference which crashes the server. It could be used by an external att

How urgent is CVE-2022-37797?

Priority 63/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · lighttpd vulnerabilities

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References

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