CVE
Roundcube Webmail before 1.6.21 and 1.7.6 IMAP Command Injection via _uid
Only Roundcube Webmail before 1.6.21, and 1.7.0 through 1.7.5, is affected, and only when messages_cache is enabled. Fixed in 1.6.21 and 1.7.6.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.6.21, 1.7.6
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. messages_cache is enabled
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- 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? →
- 19/100 · 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
Summary
Roundcube Webmail has an IMAP command injection flaw in the _uid parameter when messages_cache is enabled, which lets attackers inject IMAP commands using CRLF characters. Remotely, without logging in, an attacker can lure a logged-in user into opening a crafted GET link to mail/show or mail/get, which can delete messages, change flags, or grant mailbox access via SETACL.
Read the original description
Roundcube Webmail before 1.6.21 and 1.7.x before 1.7.6 contains an IMAP command injection vulnerability that allows attackers to inject commands via CRLF in the _uid parameter when messages_cache is enabled. Attackers can lure logged-in victims into opening crafted GET links to mail/show or mail/get, executing IMAP commands that delete messages, change flags, or grant mailbox access via SETACL.
Who should check
Teams running Roundcube Webmail 1.6.x before 1.6.21 or 1.7.x before 1.7.6 with messages_cache enabled
Read the source excerpt
“allows attackers to inject commands via CRLF in the _uid parameter when messages_cache is enabled”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.4/10CVSS 7.4
- No patch0/5No signal
What would change the score
- Would score about 69 if added to CISA KEV
- Would score about 64 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
messages_cache is enabledUpgrade to a fixed version: 1.6.21, 1.7.6.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126813 (Roundcube Webmail before 1.6.21 and 1.7.6 IMAP Command Injection via _uid), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126813 (entry last updated 2026-11-11):
Affected:
- Roundcube Webmail: fixed in 1.6.21; from 1.7.0, fixed in 1.7.6
Fixed versions: 1.6.21, 1.7.6.
Conditions (all must be true for the bug to be hit):
- messages_cache is enabled (source: https://www.vulncheck.com/advisories/roundcube-webmail-before-1.6.21-and-1.7.6-imap-command-injection-via-uid)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, a user action.
CISA KEV: CVE-2026-126813 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126813 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://roundcube.net/news/2026/11/09/security-updates-1.6.21-and-1.7.6
- https://github.com/roundcube/roundcubemail/commit/4cb1cf106b9ca5d465ed4924f2fab5d5108edfeb
- https://github.com/roundcube/roundcubemail/commit/d1dda13597ceed9df49d434a8d88b758bcf6ef5c
- https://github.com/roundcube/roundcubemail/commit/2ea63692178cab5cea486c7c630901b7f6852c80
- https://github.com/roundcube/roundcubemail/blob/1.7.5/program/lib/Roundcube/rcube_imap_generic.php#L2892
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.21
- https://github.com/roundcube/roundcubemail/releases/tag/1.7.6
- https://www.vulncheck.com/advisories/roundcube-webmail-before-1.6.21-and-1.7.6-imap-command-injection-via-uid
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126813
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126813"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- Roundcube Webmail
fixed in 1.6.21; From 1.7.0 · fixed in 1.7.6
Evidence 10
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 7
- Patch
- Patch
- Patch
- Repository
- Repository
Show all 7 sourcesShow fewer sources
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126813
Is CVE-2026-126813 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?
CRLF characters in the _uid parameter let attackers inject extra IMAP commands. Those commands can delete messages, change flags, or grant mailbox access through SETACL.Source: vulncheck.com
Which versions are affected by CVE-2026-126813?
Webmail: before 1.6.21; from 1.7.0 before 1.7.6.Source: cve.now feed data
Am I affected, and how do I check?
Roundcube Webmail before 1.6.21, and 1.7.0 through 1.7.5. The issue requires messages_cache to be enabled, so check that setting in the Roundcube configuration and compare the installed version against these ranges.Source: vulncheck.com
How do I fix CVE-2026-126813?
Upgrade to Roundcube Webmail 1.6.21 if you run the 1.6 line, or to 1.7.6 if you run the 1.7 line.Source: vulncheck.com