Posta before v0.18.0 SSRF via Webhook URL
- Exploited
- No known exploitation
- Fix
- Fixed in v0.18.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: v0.18.0.
- Last modified
- 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? →
- 8/100 · provisional
- 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
Posta, before version 0.18.0, contains a server-side request forgery flaw in its webhook feature that lets a logged-in user with edit rights make the server send POST requests to internal destinations, such as loopback, private-network, or cloud metadata addresses. It can be reached remotely over the network with low-privilege credentials and no user interaction, and an attacker can read delivery status codes and error messages to probe internal hosts and ports.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Posta before v0.18.0 contains a server-side request forgery vulnerability that allows authenticated users with edit rights to make the backend send POST requests to internal destinations by creating webhooks with arbitrary URLs. Attackers can target loopback, private-network or cloud metadata addresses and read delivery status codes and error strings to probe internal hosts and ports.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.3/10CVSS 5.3
- No patch0/5No signal
What would change the score
- Would score about 63 if added to CISA KEV
- Would score about 58 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: v0.18.0.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- goposta posta
fixed in v0.18.0
Evidence 6
- Patch
- Patch
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-123204
Is CVE-2026-123204 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-2026-123204?
posta: before v0.18.0.Source: cve.now feed data
How do I fix CVE-2026-123204?
Upgrade to a fixed version: v0.18.0.Source: cve.now feed data