Cross-site Scripting in Progress Telerik Fiddler Everywhere
Fiddler Everywhere 8.3.0 and earlier is affected when a user opens a specially crafted SAZ session archive. The issue is fixed in 8.4.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 8.3.0
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Progress Telerik Fiddler Everywhere version 8.3.0 and earlier Victim must open a specially crafted SAZ file containing a cross-site scripting payload in a session URL
- 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? →
- 13/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- 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
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Cross-site scripting in Progress Telerik Fiddler Everywhere lets an attacker run backend IPC commands on a local machine if a user is tricked into opening a specially crafted SAZ file. The attacker must be on the same system, needs no login, and depends on the user opening the file.
Read the original description
Improper neutralization of input in the sessions grid in Progress Telerik Fiddler Everywhere 8.3.0 and earlier allows an attacker to execute backend IPC commands by convincing a user to open a specially crafted SAZ file.
cve.now Index
- Exploitation0/40No signal
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.3/10CVSS 7.3, total technical impact per CISA
- 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 23 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Progress Telerik Fiddler Everywhere version 8.3.0 and earlier Victim must open a specially crafted SAZ file containing a cross-site scripting payload in a session URLUpgrade to a fixed version: 8.3.0.
Workaround: Do not open SAZ files from untrusted sources.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Progress Software Progress® Telerik® Fiddler® Everywhere
fixed in 8.3.0
Evidence 1
- Advisory
Corrections
None so far.
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Questions about CVE-2026-104656
Is CVE-2026-104656 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
What does this mean?
This is a cross-site scripting flaw. A session archive (SAZ) file containing a script payload in a session URL can run backend IPC commands, such as one that appends a text log entry to an arbitrary file.Source: telerik.com
Which versions are affected by CVE-2026-104656?
Progress® Telerik® Fiddler® Everywhere: before 8.3.0.Source: cve.now feed data
Am I affected, and how do I check?
Progress Telerik Fiddler Everywhere version 8.3.0 and earlier is affected, and the attack requires a user to open a specially crafted SAZ file. To check a installed copy, compare its version number with 8.3.0.Source: telerik.com
How do I fix CVE-2026-104656?
Upgrade to Fiddler Everywhere 8.4.0, which addresses the issue. Until then, do not open SAZ files from untrusted sources.Source: telerik.com