CVE-2026-27122
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
- Record
CVE-2026-27122- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2026-7538
svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
- Record
EUVD-2026-7538- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-m56q-vw4c-c2cp
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
When using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected.
- Record
GHSA-m56q-vw4c-c2cp- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
NVD
svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
- Record
CVE-2026-27122- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
- Record
CVE-2026-27122- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVGHSA-m56q-vw4c-c2cp
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
When using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected.
- Record
GHSA-m56q-vw4c-c2cp- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - Weakness
- CWE-79
- Updated
- 2026-11-02
Show 5 moreShow less
OSVCLSA-2026-1775953999 No score
TuxCare security update for svelte (4 CVEs)
TuxCare rebuilt svelte to address 4 CVEs. Fixed in 4.2.20-tuxcare.1.
- Record
CLSA-2026-1775953999- Updated
- 2026-11-02
OSVCLSA-2026-1776040402 No score
TuxCare security update for svelte (5 CVEs)
TuxCare rebuilt svelte to address 5 CVEs. Fixed in 3.59.2-tuxcare.1.
- Record
CLSA-2026-1776040402- Updated
- 2026-11-02
OSVCLSA-2026-1776126838 No score
TuxCare security update for svelte (6 CVEs)
TuxCare rebuilt svelte to address 6 CVEs. Fixed in 2.16.1-tuxcare.1.
- Record
CLSA-2026-1776126838- Updated
- 2026-11-02
OSVCLSA-2026-1776213244 No score
TuxCare security update for svelte (6 CVEs)
TuxCare rebuilt svelte to address 6 CVEs. Fixed in 1.64.1-tuxcare.1.
- Record
CLSA-2026-1776213244- Updated
- 2026-11-02
OSVCLSA-2026-1776213252 No score
TuxCare security update for svelte (6 CVEs)
TuxCare rebuilt svelte to address 6 CVEs. Fixed in 0.3.0-tuxcare.1.
- Record
CLSA-2026-1776213252- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
sveltenpm |
through 5.51.4 | 5.51.5 |
svelteTuxCare:npm From an advisory covering 4 CVEs |
4.2.20-tuxcare.0 up to 4.2.20-tuxcare.1, plus listed versions 4.2.20 |
4.2.20-tuxcare.1 |
svelteTuxCare:npm From an advisory covering 5 CVEs |
3.59.2-tuxcare.0 up to 3.59.2-tuxcare.1, plus listed versions 3.59.2 |
3.59.2-tuxcare.1 |
svelteTuxCare:npm From an advisory covering 6 CVEs |
2.16.1-tuxcare.0 up to 2.16.1-tuxcare.1, plus listed versions 2.16.1 |
2.16.1-tuxcare.1 |
svelteTuxCare:npm From an advisory covering 6 CVEs |
1.64.1-tuxcare.0 up to 1.64.1-tuxcare.1, plus listed versions 1.64.1 |
1.64.1-tuxcare.1 |
svelteTuxCare:npm From an advisory covering 6 CVEs |
0.3.0-tuxcare.0 up to 0.3.0-tuxcare.1, plus listed versions 0.3.0 |
0.3.0-tuxcare.1 |
sveltenpm |
before 5.51.5 | 5.51.5 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-27122 is a medium vulnerability (CVSS 5.1) in Svelte, published February 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in svelte 5.51.5.