Heap-based buffer overflow in the parse_string function in libs/esl/src/esl_json.c in FreeSWITCH before 1.4.23 and 1.6.x before 1.6.2 allows
Heap-based buffer overflow in the parse_string function in libs/esl/src/esl_json.c in FreeSWITCH before 1.4.23 and 1.6.x before 1.6.2 allows remote attackers to execute arbitrary code via a trailing \u in a json string to cJSON_Parse.
- Published
- Oct 5, 2015
- Updated
- Jun 16, 2026
- EPSS
- 4.7% · 91th percentile
- CWE
- CWE-119
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Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 4.7%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| freeswitch | freeswitch | cpe:2.3:a:freeswitch:freeswitch |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- freeswitch freeswitchup to 1.4.21 inclusive
- freeswitch freeswitch1.6.0
Same product
freeswitch: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-19492FreeSWITCH 1.6.10 through 1.10.1 has a default password in event_socket.conf.xml.48Plan
- CVE-2026-49841FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read39Monitor
- CVE-2026-49840FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing36Monitor
- CVE-2021-41105FreeSWITCH susceptible to Denial of Service via invalid SRTP packets31Monitor
- CVE-2021-37624FreeSWITCH does not authenticate SIP MESSAGE requests, leading to spam and message spoofing31Monitor
- CVE-2018-19911FreeSWITCH through 1.8.2, when mod_xml_rpc is enabled, allows remote attackers to execute arbitrary commands via the api/system or txtapi/sy31Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- P · data can be read
- Integrity
- P · data or configuration can be modified
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- P
- Integrity impact
- P
- Availability impact
- P
Weakness class (CWE)
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory BufferCVSS vector
AV:N/AC:L/Au:N/C:P/I:P/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Buffer ManipulationCAPEC-123likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.securityfocus.com/archive/1/536569/100/0/threaded
- freeswitch.org/stash/projects/FS/repos/freeswitch/commits/cf8925
Vendor advisories and official records. Exploit/PoC links are deliberately left out.