CVE-2017-16881: b3log Symphony (aka Sym) 2.2.0 does not properly address XSS in JSON objects, as demonstrated by a crafted use

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MEDIUM 6.1DOWNGRADE

CVE-2017-16881 is a medium-severity flaw (CVSS 6.1) affecting symphony. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

b3log Symphony (aka Sym) 2.2.0 does not properly address XSS in JSON objects, as demonstrated by a crafted userAvatarURL value to /settings/avatar, related to processor/AdminProcessor.java, processor/ArticleProcessor.java, processor/UserProcessor.java, service/ArticleQueryService.java, service/AvatarQueryService.java, and service/CommentQueryService.java.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-79
Published	2017-11-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: symphony project

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

Am I affected?

Timeline

2017-11-18 13:29 UTCPublished CVE record published
2026-06-17 01:10 UTCUpdated Record last modified

symphony project symphony DOWNGRADE

Affected: 2.2.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.2.0 (Debian / Ubuntu)

apt-cache madison symphony sudo apt install symphony=<VERSION_BEFORE_2.2.0> sudo apt-mark hold symphony

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

dnf --showduplicates list symphony sudo dnf downgrade symphony-<VERSION_BEFORE_2.2.0> sudo dnf versionlock add symphony

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.

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-2017-16881?

symphony: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-16881 being exploited?

CVE-2017-16881 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-2017-16881 affect?

CVE-2017-16881 affects symphony. Severity is medium (CVSS 6.1). b3log Symphony (aka Sym) 2.2.0 does not properly address XSS in JSON objects, as demonstrated by a crafted userAvatarURL value to /settings/avatar, related to processor/AdminProcessor.java, processor/ArticleProcessor.java, processor/UserPro

How urgent is CVE-2017-16881?

Priority 41/100. Public exploit reference

Software pages

Java vulnerabilities

Related CVEs

CVE-2020-25912 CRITICAL 9.1 DOWNGRADE A XML External Entity (XXE) vulnerability was discovered in symphony\lib\toolkit\class.xmlelement.php in Symph
CVE-2020-25343 MEDIUM 5.4 DOWNGRADE Cross-site scripting (XSS) vulnerabilities in Symphony CMS 3.0.0 allow remote attackers to inject arbitrary we
CVE-2020-17405 HIGH 8.8 DOWNGRADE This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Se
CVE-2020-15071 MEDIUM 6.1 DOWNGRADE content/content.blueprintsevents.php in Symphony CMS 3.0.0 allows XSS via fields['name'] to appendSubheading.
CVE-2019-9142 MEDIUM 6.1 UPGRADE An issue was discovered in b3log Symphony (aka Sym) before v3.4.7

References

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