FrankenPHP before 1.13.4 Cross-Request Response Header Leak in Worker Mode
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.13.4
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 1.13.4.
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Data gap: No advisory context yet
- Reach17/20Affects PHP (a widely deployed server, runtime, framework or database)
- Severity6.3/10CVSS 6.3
- No patch0/5No signal
What would change the score
- Would score about 85 if added to CISA KEV
- Would score about 80 if CISA's SSVC rates exploitation active
- Would score about 45 if advisories confirm default setups are exposed
CVE-2026-122233 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.3 (medium) and affects frankenphp; fixed in 1.13.4.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 40/100 · provisional
- Fix
- Fixed in 1.13.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FrankenPHP, a PHP application server, is affected in its worker mode, where a request can read HTTP response headers left behind by earlier requests handled on the same worker thread. An attacker can do this remotely, without logging in, and could see sensitive headers such as other users' Set-Cookie or token values from backend APIs.
Read the original description
FrankenPHP before 1.13.4 contains an information disclosure vulnerability in worker mode that fails to clear last HTTP stream response headers between requests, because the reset only happens in RSHUTDOWN, which worker requests skip. Later requests calling http_get_last_response_headers() can read headers fetched by earlier requests on the same worker thread, exposing other users' Set-Cookie or token headers from backend APIs.
What to do
Upgrade to a fixed version: 1.13.4.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- php frankenphp
fixed in 1.13.4
Evidence 4
- Advisory
- Patch
- Repository
- Link
Corrections
None so far.
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Questions about CVE-2026-122233
Is CVE-2026-122233 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-122233?
frankenphp: before 1.13.4.Source: cve.now feed data
How do I fix CVE-2026-122233?
Upgrade to a fixed version: 1.13.4.Source: cve.now feed data